I played around with OBS a couple times trying to figure out what the issue was, I'm not sure which log is correct log to use. I'm looking through them trying to find an error report, is this not it?
19:21:22.734: [CoreAudio encoder]: CoreAudio AAC encoder not installed on the system or couldn't be loaded
19:21:22.736: Failed to load 'en-US' text for module: 'decklink-captions.dll'
19:21:22.741: Failed to load 'en-US' text for module: 'decklink-ouput-ui.dll'
19:21:22.771: [AMF] Unable to load 'amfrt64.dll', error code 126.
19:21:22.774: [AMF] AMF Test failed due to one or more errors.
19:21:22.774: Failed to initialize module 'enc-amf.dll'
19:21:22.925: Skipping module '../../obs-plugins/64bit/libcef.dll', not an OBS plugin
19:21:22.946: Skipping module '../../obs-plugins/64bit/libEGL.dll', not an OBS plugin
19:21:22.956: Skipping module '../../obs-plugins/64bit/libGLESv2.dll', not an OBS plugin
19:21:22.996: [obs-browser]: Version 2.14.3
19:21:22.996: [obs-browser]: CEF Version 75.1.16+g16a67c4+chromium-75.0.3770.100
19:21:23.061: NVENC supported
19:21:23.066: [noise suppress: Nvidia RTX denoiser disabled, redistributable not found]
19:21:23.204: Couldn't find VLC installation, VLC video source disabled
19:21:23.220: A DeckLink iterator could not be created. The DeckLink drivers may not be installed
19:21:23.220: No blackmagic support
I've found that it seems to get to ~35 minutes consistently and then errors out. I can successfully record shorter pieces, but not longer than that. I was worried I didn't have enough space for files to output too, and I've since moved output to a dive with significantly more space. And I'm still having the same issue.
You can either use the 'upload' function in OBS and paste the URL here (current is for the current run, since you last opened OBS, last is for the previous session ending when you closed OBS last) or drag and drop the file itself directly to your forum post to attach it as a textfile.
So, going off of the ability to analyze a log, some identified issues were not running OBS as administrator and outputting to MP4. So I changed those things, and I've been recording steady for an hour and 45 minutes. So that seems to have fixed the issue, whatever it was.