A couple of suggestions and thoughts:
Just because a camera “works” one month, then doesn’t “work” the next month doesn’t mean that it’s an Apple-approved camera for that version of software. That’s why I suggested looking at the Apple link to approved devices. Cameras and decks and converters that are NOT approved may very well “work” one or two or three or 20 times, but then NOT work the next 20 times. That’s why they are not listed as approved devices – they fail to work consistently. You still have not mentioned if your camera appears on any of Apple’s approved device lists.
I can’t compare setup with your camera to my camera because they are different devices, but I can review the setup process with mine in hope of finding some step or procedure you may be missing.
I plug in all devices before opening FCE HD 3.5.1.
I select the VCR option on the camera.
I select the Analog Video to Digital Video option on the camera when using it as an analog converter for Betacam SP media or any other analog media; otherwise, the camera defaults to DV media output if this option is left unchecked.
I select either DV-NTSC Firewire Basic under Easy Setup for capturing DV media or DV-NTSC DV-Converter for capturing analog media.
I open the capture window and start capturing video.
Sometimes, especially when beginning to edit AFTER capture, I have to refresh the converters and monitors before the video and audio “pops up” on the monitor and speakers. Maybe refreshing or toggling the camera prior to capture will help FC recognize the device?
Hope this helps.