I’ve been having the same problem with the imacs and canons at my college (Cal, Go bears!) which I chalked up to the school not having the money for the latest equipment. Especially since my hackintosh at home had no problems with my cnanon vixia hv40. However I always have the canon on and plugged in when I start up my pc and then final cut. After months of no issues I started up once and I can’t solve this.
An easy way to check the firewire connection is to look in the system profiler and select the firewire tab. Mine literally reports my specific camera model and yours should too. At that point its something to do with either a software conflict/glitch or something with the cameras. the schools gear randomly worked on and off again (with a few of the imacs working at any given time, but no one really sure why which one was working at the moment) and I can’t figure out for the life of me why camera switching would be so tempermental on this software.
If anyone makes any progress on this, and actually understands why please let me know. I’m beginning work as a mac genius myself soon so maybe they’ll teach me something related to this and I’ll update you guys if I’ learn anything first, but I doubt it.