I have exactly the same problem. I don’t know if Jeffrey already solved the problem, but here’s the steps to reproduce:
1. Create a blank generator file in Motion 5.
2. Add a new Drop Zone (spanning the default duration of 10 seconds)
3. Save the file
4. Open up the generator template in a new Final Cut Pro X project
5. Browse to a movieclip that’s long enough
6. Drag the movieclip to the Drop Zone well
7. Play the project…
8. …the movieclip in the Drop Zone is a still (first frame)
I dunno what’s going wrong. Anyone?