I am having the same problem. I tested on 3 different windows 10 computers. I can see the IP Cam stream on VLC but OBS shows only black screen. If I use transform and fit to window, it shows me black rectangle.
Log:
09:40:11.992: CPU Name: Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz
09:40:11.992: CPU Speed: 2394MHz
09:40:11.992: Physical Cores: 2, Logical Cores: 4
09:40:11.992: Physical Memory: 8081MB Total, 4788MB Free
09:40:11.992: Windows Version: 10.0 Build 15063 (revision: 296; 64-bit)
09:40:11.992: Running as administrator: false
09:40:11.992: Aero is Enabled (Aero is always on for windows 8 and above)
09:40:11.993: Portable mode: false
09:40:12.028: OBS 18.0.1 (64bit, windows)
09:40:12.028: ---------------------------------
09:40:12.033: ---------------------------------
09:40:12.033: audio settings reset:
09:40:12.033: samples per sec: 44100
09:40:12.033: speakers: 2
09:40:12.061: ---------------------------------
09:40:12.061: Initializing D3D11..
09:40:12.061: Available Video Adapters:
09:40:12.065: Adapter 1: Intel(R) HD Graphics Family
09:40:12.065: Dedicated VRAM: 117964800
09:40:12.065: Shared VRAM: 2147483648
09:40:12.065: output 1: pos={0, 0}, size={1366, 768}, attached=true
09:40:12.101: Loading up D3D11 on adapter Intel(R) HD Graphics Family (0)
09:40:12.116: D3D11 loaded sucessfully, feature level used: 45056
09:40:13.160: ---------------------------------
09:40:13.160: video settings reset:
09:40:13.160: base resolution: 640x360
09:40:13.160: output resolution: 640x360
09:40:13.160: downscale filter: Bicubic
09:40:13.160: fps: 5/1
09:40:13.160: format: NV12
09:40:13.161: Audio monitoring device:
09:40:13.161: name: Default
09:40:13.161: id: default
09:40:13.161: ---------------------------------
09:40:13.184: Required module function 'obs_module_load' in module '../../obs-plugins/64bit/chrome_elf.dll' not found, loading of module failed
09:40:13.203: [CoreAudio encoder]: CoreAudio AAC encoder not installed on the system or couldn't be loaded
09:40:13.232: [AMF Encoder] Unable to load 'amfrt64.dll', error code 126.
09:40:13.386: Required module function 'obs_module_load' in module '../../obs-plugins/64bit/libcef.dll' not found, loading of module failed
09:40:13.397: Required module function 'obs_module_load' in module '../../obs-plugins/64bit/libEGL.dll' not found, loading of module failed
09:40:13.421: Required module function 'obs_module_load' in module '../../obs-plugins/64bit/libGLESv2.dll' not found, loading of module failed
09:40:13.440: Failed to load 'en-US' text for module: 'obs-browser.dll'
09:40:13.440: [browser_source: 'Version: 1.29.0']
09:40:13.477: LoadLibrary failed for 'nvEncodeAPI64.dll': The specified module could not be found.
09:40:13.477: (126)
09:40:13.786: VLC found, VLC video source enabled
09:40:14.805: ---------------------------------
09:40:14.805: Loaded Modules:
09:40:14.805: win-wasapi.dll
09:40:14.805: win-mf.dll
09:40:14.805: win-dshow.dll
09:40:14.805: win-decklink.dll
09:40:14.805: win-capture.dll
09:40:14.805: vlc-video.dll
09:40:14.805: text-freetype2.dll
09:40:14.805: rtmp-services.dll
09:40:14.805: obs-x264.dll
09:40:14.805: obs-vst.dll
09:40:14.805: obs-transitions.dll
09:40:14.805: obs-text.dll
09:40:14.805: obs-qsv11.dll
09:40:14.805: obs-outputs.dll
09:40:14.805: obs-filters.dll
09:40:14.805: obs-ffmpeg.dll
09:40:14.805: obs-browser.dll
09:40:14.805: image-source.dll
09:40:14.805: frontend-tools.dll
09:40:14.805: enc-amf.dll
09:40:14.805: coreaudio-encoder.dll
09:40:14.805: ==== Startup complete ===============================================
09:40:14.806: Service '' not found
09:40:14.816: All scene data cleared
09:40:14.816: ------------------------------------------------
09:40:14.965: WASAPI: Device 'Speakers (Conexant SmartAudio HD)' initialized
09:40:15.423: WASAPI: Device 'Microphone (Conexant SmartAudio HD)' initialized
09:40:15.424: [Media Source 'Media Source']: settings:
09:40:15.424: input: rtsp://5.11.142.133/video3
09:40:15.424: input_format:
09:40:15.424: is_looping: no
09:40:15.424: is_forcing_scale: yes
09:40:15.424: is_hw_decoding: yes
09:40:15.424: is_clear_on_media_end: yes
09:40:15.424: restart_on_activate: yes
09:40:15.432: Switched to scene 'Scene'
09:40:15.433: ------------------------------------------------
09:40:15.433: Loaded scenes:
09:40:15.433: - scene 'Scene':
09:40:15.433: - source: 'Media Source' (ffmpeg_source)
09:40:15.433: ------------------------------------------------
09:40:15.496: adding 23 milliseconds of audio buffering, total audio buffering is now 23 milliseconds