I applied HS filters to the elements but found that transparency failed on embedded clips of flare - not in Motion but in FCPx. Furthermore, dropzones were working differently.

These projects are not very expensive so I didn't expect too much when I put a support email in. I was pleasantly surprised by the response.

First Clips in DropZones work differently in FCPx 10.1 - my bad I should have done a little more research (Now the position of the playhead at the point of application is used rather than the beginning of the selection) .

Transparency in Motion and the way that video is inherited into the dropzone in FCPx is quite complex where there is another transparent video clip in the project. The upshot is that if you apply a HS filter to a group of elements then the transparent clip in that element has the equal and opposite HS filter applied.

Jakub Jaroszek of MotionVFX send me a screenshot of his Motion project with all the elements expanded and an explanation of what to do where.

I thought this was worthy of a note on PV.