Hi Don,
Thank you for your response. I don’t have any markers in there at the moment (I had put some in early on but took them out when things weren’t working). Someone also told me that Motion also doesn’t like it when things start ‘off frame’ so even though not ideal, I even moved the mask well into frame to start … same results: works fine in Motion, previews fine in FCPX thumbnail, but the moment it’s applied to the timeline, nada. It’s really rather frustrating that something that should be so simple would cause so much headache.
Thanks again Don. Hopefully someone else will have some idea.
B