When attempting to capture footing into FCP from the Canon HV10 camcorder, I got the following message:

It turns out that something in either FCP or the HV10 is very finicky about the camcorder’s power source. Here are a few solutions:

1. Close the Log & Capture window, plug the camcorder into wall power, re-open Log & Capture.
2. Open iMovieHD. Just opening iMovieHD seems to be enough to kickstart the FireWire connection. iMovieHD was able to read and capture from the camcorder even when FCP couldn’t.

I haven’t had the issue pop up at all when running on wall power. It may be related to a low charge camcorder battery.

Occasionally, when correcting the state of the camcorder, FCP’s Log & Capture window gets stuck and won’t close. I haven’t found any way to close it other than restarting FCP.