I'm having the same issue with the same mixer (x1204usb) - The difference is mine was actually working and I've done a number of live streams with this mixer and OBS. Now, all of a sudden, with no settings being changed, the audio is going through the mixer fine but not showing up in OBS through the input meters. I tried recording to see if it was just the meters but no, no sound was coming in.
I'm going to post this as a new thread because it makes no sense that it worked for weeks and now isn't. I tried different usb ports and cables, restarting, etc.
Log:
17:02:09.177: CPU Name: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
17:02:09.177: CPU Speed: 2500MHz
17:02:09.177: Physical Cores: 2, Logical Cores: 4
17:02:09.177: Physical Memory: 16384MB Total
17:02:09.177: OS Name: Mac OS X (NSMACHOperatingSystem)
17:02:09.177: OS Version: Version 10.13.6 (Build 17G66)
17:02:09.177: Kernel Version: 17.7.0
17:02:09.249: hotkeys-cocoa: Using layout 'com.apple.keylayout.US'
17:02:09.250: Portable mode: false
17:02:10.065: OBS 25.0.7 (mac)
17:02:10.065: ---------------------------------
17:02:10.068: ---------------------------------
17:02:10.068: audio settings reset:
17:02:10.068: samples per sec: 44100
17:02:10.068: speakers: 2
17:02:10.168: ---------------------------------
17:02:10.168: Initializing OpenGL...
17:02:10.207: Loading up OpenGL on adapter Intel Inc. Intel HD Graphics 4000 OpenGL Engine
17:02:10.207: OpenGL loaded successfully, version 4.1 INTEL-10.36.19, shading language 4.10
17:02:10.343: ---------------------------------
17:02:10.343: video settings reset:
17:02:10.343: base resolution: 1280x720
17:02:10.343: output resolution: 1280x720
17:02:10.343: downscale filter: Bicubic
17:02:10.343: fps: 30/1
17:02:10.343: format: NV12
17:02:10.343: YUV mode: 601/Partial
17:02:10.343: NV12 texture support not available
17:02:10.344: Audio monitoring device:
17:02:10.344: name: Default
17:02:10.344: id: default
17:02:10.345: ---------------------------------
17:02:10.406: Failed to load 'en-US' text for module: 'decklink-ouput-ui.so'
17:02:10.470: os_dlopen(libpython3.7m.dylib->libpython3.7m.dylib): dlopen(libpython3.7m.dylib, 257): image not found
17:02:10.470:
17:02:10.470: [Python] Could not load library: libpython3.7m.dylib
17:02:10.796: A DeckLink iterator could not be created. The DeckLink drivers may not be installed
17:02:10.796: No blackmagic support
17:02:10.891: [VideoToolbox encoder]: Adding VideoToolbox H264 encoders
17:02:11.340: [obs-browser]: Version 2.8.6
17:02:11.834: os_dlopen(/Applications/VLC.app/Contents/MacOS/lib/libvlccore.dylib->/Applications/VLC.app/Contents/MacOS/lib/libvlccore.dylib): dlopen(/Applications/VLC.app/Contents/MacOS/lib/libvlccore.dylib, 257): image not found
17:02:11.834:
17:02:11.834: Couldn't find VLC installation, VLC video source disabled
17:02:11.836: [obs-ndi] hello ! (version 4.7.1)
17:02:11.836: [obs-ndi] Trying ''
17:02:11.836: [obs-ndi] Trying '/usr/lib'
17:02:11.836: [obs-ndi] Trying '/usr/local/lib'
17:02:11.836: [obs-ndi] Found NDI library at '/usr/local/lib/libndi.4.dylib'
17:02:11.840: [obs-ndi] NDI runtime loaded successfully
17:02:11.841: [obs-ndi] NDI library initialized successfully (NDI SDK APPLE 14:35:05 Dec 19 2019 4.1.3)
17:02:11.844: ---------------------------------
17:02:11.844: Loaded Modules:
17:02:11.844: obs-ndi.so
17:02:11.844: vlc-video.so
17:02:11.844: text-freetype2.so
17:02:11.844: rtmp-services.so
17:02:11.844: obs-x264.so
17:02:11.844: obs-vst.so
17:02:11.844: obs-transitions.so
17:02:11.844: obs-outputs.so
17:02:11.844: obs-libfdk.so
17:02:11.844: obs-filters.so
17:02:11.844: obs-ffmpeg.so
17:02:11.844: obs-browser.so
17:02:11.844: mac-vth264.so
17:02:11.844: mac-syphon.so
17:02:11.844: mac-decklink.so
17:02:11.844: mac-capture.so
17:02:11.844: mac-avcapture.so
17:02:11.844: linux-jack.so
17:02:11.844: image-source.so
17:02:11.844: frontend-tools.so
17:02:11.844: decklink-ouput-ui.so
17:02:11.844: coreaudio-encoder.so
17:02:11.844: ---------------------------------
17:02:11.844: os_dlopen(../obs-plugins/obs-browser->../obs-plugins/obs-browser.so): dlopen(../obs-plugins/obs-browser.so, 257): image not found
17:02:11.844:
17:02:11.894: ==== Startup complete ===============================================
17:02:11.931: All scene data cleared
17:02:11.931: ------------------------------------------------
17:02:11.971: coreaudio: device 'USB Audio CODEC ' initialized
17:02:11.972: [Loaded global audio device]: 'Mic/mixer/usb'
17:02:12.022: coreaudio: device 'USB Audio CODEC ' initialized
17:02:12.022: [Media Source 'Media Source']: settings:
17:02:12.022: input:
17:02:12.022: input_format: (null)
17:02:12.022: speed: 100
17:02:12.022: is_looping: no
17:02:12.022: is_hw_decoding: no
17:02:12.022: is_clear_on_media_end: yes
17:02:12.022: restart_on_activate: yes
17:02:12.022: close_when_inactive: no
17:02:12.111: adding 92 milliseconds of audio buffering, total audio buffering is now 92 milliseconds (source: mixer)
17:02:12.111:
17:02:13.019: Webcam: Selected device 'HD Pro Webcam C920'
17:02:13.027: Webcam: Using preset 1280x720
17:02:13.223: [obs-ndi] started A/V threads for source 'MACS-MACBOOK-PRO.LOCAL (OBS)'
17:02:13.223: [obs-ndi] A/V thread for 'NDI™ Source' started
17:02:13.346: Switched to scene 'CrashChessDummy'
17:02:13.346: ------------------------------------------------
17:02:13.346: Loaded scenes:
17:02:13.346: - scene 'CrashChessDummy':
17:02:13.350: - source: 'Chessbattle' (image_source)
17:02:13.350: - source: 'Webcam' (av_capture_input)
17:02:13.350: - source: 'Window Capture' (window_capture)
17:02:13.350: - source: 'CCD logo' (image_source)
17:02:13.350: - source: 'CCD piece' (image_source)
17:02:13.350: - source: 'mixer' (coreaudio_input_capture)
17:02:13.350: - scene 'DJ stream':
17:02:13.350: - source: 'Background' (image_source)
17:02:13.350: - source: 'back 2' (image_source)
17:02:13.350: - source: 'logo' (image_source)
17:02:13.350: - source: 'Mic/mixer/usb' (coreaudio_input_capture)
17:02:13.350: - source: 'NDI™ Source' (ndi_source)
17:02:13.350: - source: 'Webcam' (av_capture_input)
17:02:13.351: - scene 'DJ - modern tv':
17:02:13.351: - source: 'tv on wall' (image_source)
17:02:13.351: - source: 'Mic/mixer/usb' (coreaudio_input_capture)
17:02:13.351: - source: 'ipad/cam group' (group)
17:02:13.351: - source: 'ipad' (image_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'NDI™ Source' (ndi_source)
17:02:13.351: - source: 'logo' (image_source)
17:02:13.351: - source: 'Media Source' (ffmpeg_source)
17:02:13.351: - source: 'Social links' (image_source)
17:02:13.351: - scene 'DJ - modern tv (L)':
17:02:13.351: - source: 'Mic/mixer/usb' (coreaudio_input_capture)
17:02:13.351: - source: 'Main' (group)
17:02:13.351: - source: 'tv on wall' (image_source)
17:02:13.351: - source: 'NDI™ Source' (ndi_source)
17:02:13.351: - source: 'ipad/cam group' (group)
17:02:13.351: - source: 'ipad' (image_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'logo' (image_source)
17:02:13.351: - source: 'Media Source' (ffmpeg_source)
17:02:13.351: - source: 'Social links' (image_source)
17:02:13.351: - scene 'DJ - theatre':
17:02:13.351: - source: 'Theatre' (image_source)
17:02:13.351: - source: 'NDI™ Source' (ndi_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'logo 2' (image_source)
17:02:13.351: - source: 'logo low' (image_source)
17:02:13.351: - source: 'Social links' (image_source)
17:02:13.351: - scene 'DJ - old tv':
17:02:13.351: - source: 'TV background' (image_source)
17:02:13.351: - source: 'ipad/cam group 2' (group)
17:02:13.351: - source: 'ipad' (image_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'logo' (image_source)
17:02:13.351: - source: 'NDI™ Source' (ndi_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'Social links' (image_source)
17:02:13.351: - scene 'DJ - old tv (L)':
17:02:13.351: - source: 'TV background' (image_source)
17:02:13.351: - source: 'ipad/cam group 2' (group)
17:02:13.351: - source: 'ipad' (image_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'logo' (image_source)
17:02:13.351: - source: 'NDI™ Source' (ndi_source)
17:02:13.351: - source: 'Webcam' (av_capture_input)
17:02:13.351: - source: 'Social links' (image_source)
17:02:13.351: - source: 'Towlie gif' (image_source)
17:02:13.351: - source: 'Bart ' (image_source)
17:02:13.351: - source: 'towlie ' (image_source)
17:02:13.351: ------------------------------------------------
Any help is appreciated.