Andrew,
we’ve had this problem before: in our case it stemmed from a corrupt motion template generated by Automotion. We narrowed it down to a portion of the text, in french, that had an accent in it. That same template was being used throughout the program but only when filled with that text did it cause a problem.
I am still working on finding the source of the problem as our titles are generated by PA’s in Excel, saved as txt files, then imported into Automotion. Methinks it could have something to do with text coding, either in Excel or in Automotion although until now I have not been able to reproduce this from scratch.
The good news is that XDCAM transfer will stall on it with the error message, whereas MXF4MAC will not do anything nor tell you anything is wrong…and won’t work the next time you want to use it, unless you relaunch FCP…
Hope this helps,
Patrice