Did some more troubleshooting, and it seems to be related to internal temperature. Once the temp gets over 42C, the image from the sensor freezes. I can still see and interact with all menus as normal, and nothing else is frozen. If I kick up the fan speed and lower the temp back below 39C, I can change codec and the image comes back. If the temp is above 41C or 42C then the image goes completely black when the image is frozen and I change codec. If i reboot while the temp is still over 41C, then it just boots to black, no image whatsoever, until I cool it back down and toggle between codecs while under 40C.
It’s stable if it’s under 41C. Obviously, I can’t keep the fans running at 80% while I’m recording.
If the image goes black and I shutdown, I won’t get an image after booting unless the temp as cooled below 39C.
Nothing in my build has changed in the last 4 months of using the camera so this is a new issue.