I also had experienced this, with my Sony DSR-25.
It Plays DVCPro tapes fine for playback, but through the firewire port, I get nothing….
Here was my solution…. I also have a DVCPro Camera, so I hooked up the DVCPro camera outputs into my inputs on my deck, turned on the EE passthrough on the deck, and Volia….
I have to play the tape through the camera, but it gets it into FCP via the deck and firewire…
Hope this helped you!
Darrin Martin aka Dream Master