First, this issue was between ATEM and OBS Studio...
Looks like it ended being a major USB issue. When I unplug all USB devices and plug in the ATEM first, I can then see it in OBS now. I even plugged it straight into one of my two USB-C ports (reluctantly) to make sure it has priority and enough speed. Where it was connected was a 10 port powered USB 3.1 hub. Everything was fine for days with 9 USB devices. That hub is plugged into a 5Gbps port and most everything is simple devices like keyboards, mice, BQ SW320 monitors (for weekly screen calibration and putting new hardware icc files on the monitors). I added Stream Deck about 2 weeks ago and all was fine. For some reason, some perfect storm order of initializing happened today, that perhaps got the ATEM a different place in the hub? What I don't understand is that I could see the BlackMagic device in the local Camera application crystal clear (AND at one point I plugged the ATEM directly into another USB A port (though not a 5Gbps one, vs the 10 port USB hub I have gets a 5Gbps port on my laptop). It was only OBS that couldn't use it.
?? Perhaps OBS is more demanding for the full fps and quality, and other apps are less demanding.
No clue, but my issue was a USB issue.
If you suspect a USB issue. Try to turn off/disable all USB ports, crank back up your ATEM and let it be the sole device to use USB. Also isolate it to a high speed USB port (preferrably a thunderbolt USB-C port). Then once you get OBS back to seeing your feed, start bringing back online your other USB devices one at a time.
other solutions that didn't work for me, but might for you (good troubleshooting info, is to see if you can see your webcam in another app or not before beginning):
- restart OBS after making sure all video capture sources are set to deactivate if not in use
- uninstall/reinstall the latest OBS and ATEM software (and stream deck and obs webhooks if you use those)
- run windows update and reboot if found any
- in your graphic settings (in Display Settings), make sure it is on Classic app and then browse for the OBS executable and set graphic specifications to "power saving"
- try removing all OBS scenes (back them up) and creating a single simple scene with a video capture source for the ATEM
- see if any other app is using the ATEM web camera (go to Settings | Privacy | Camera and see if any listed app says "currently in use" if so, kill the app)
- if you suspect #6 is lying and another app is actually using the webcam, use the free utility from Microsoft called "Process Explorer Search". First go to device manager and go to properties on your webcam, then Details, and choose the property "Physical Device Object name" and copy the value (this is the physical device object name for your ATEM). Switch back to the Process Explorer Search, and do a Find on a paste of the object name. It is possible that a local app has the webcam and even Microsoft's camera settings don't list it.
- Try another USB port/cable
- worst case, try what I did and turn off all USB ports, plug your ATEM into a high speed port all by itself, then check OBS to see if it is now happy with your ATEM feed, then bring the rest of your USB devices up one at a time.
I hope this helps someone else, because I did NOT see this solution any where else.