Again, I know this is an old thread, but for the benefit of any google searches that land here...
I've screwed with this for over two days now, and finally found a work-around.
After MUCH trial and error, I have found the issue here isn't really with obs. It is with the bundled version of ffmpeg.
I bypassed obs completely and started playing around with ffmpeg directly and had issues here and there as well, BUT...I found a version that worked for me.
This DOES work for me now, but who knows for how long. The workaround (this is all 64 bit arch):
Install the current version of obs (24.0.3).
Download version 4.1.4 of the SHARED library build of ffmpeg.
Extract the contents of the ffmpeg zip file.
Navigate to the \bin folder of ffmpeg.
Copy all the .dll files.
Navigate to C:\Program Files\obs-studio\bin\64bit folder (or where ever you have obs installed)
*optional* backup the original .dll files that have the same filename as the ones copied from ffmpeg (Rename and/or move the original .dll files)
paste the .dll files extracted from the ffmpeg folder above.
You can delete the ffmpeg folder if you wish.
Hope this saves someone out there some hair pulling. I've lost enough already.
-Alan