I have had Zoom fail to connect to the camera on my PC over the last couple of days. Zoom say to make sure that other camera using applications have detached. I used [ctrl][alt][del] to start the task manager and noticed that Teams was still running. So I used the end task button and the camera came on. I launched the teams app and discovered in the setting panel, the switch i.e. checkbox that keeps it running when the call ends. This was on; now its off and it seems to be behaving.