Check whether the camera itself stops
Watch the camera’s own display when the HDMI feed disappears. Check its manual for power saving, continuous live output and approved power while operating. A camera that charges from a socket can’t necessarily run from it for a whole stream.
If HDMI stops while the camera stays on, check its output mode and clean-feed settings. The camera capture checker separates those prerequisites.
When OBS loses the source
Check whether the operating system still sees the capture device. If not, use the USB dropout checks. If the device remains, close other apps using it and inspect the OBS Video Capture Device settings.
A source set to deactivate when hidden may need time to restart after a scene change. Test returning to the scene before assuming that the camera has shut down.
Repeat the failing duration
Use the intended camera mode, power, capture cable and scene changes. Record past the point where it stopped before. Keep the camera’s ventilation and setup as the maker specifies; a short preview does not prove continuous operation.