this will definitely happen if you are cutting from rushes that are in one project
into a sequence that’s in another project.
FCP cant maintain the Master Affiliate relationship between projects,
as each project is a self-contained database.
also, do you want to find the master clip for one camera?
that’s what Shift F will do.
if you want to reveal the Master Multiclip, then that is possible, but you have to create your own shortcut for that.
(you can co-opt Shift F if you want)
Tools > Keyboard Layout > Customize (or Option H)
this is probably straying fro your topic, but this is a copy/paste from a recent post i made on another list:
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it can also happen within the one project that the Master Affiliate
relationship just breaks.
it can happen with a few clips, or it can happen with all the clips.
why it happens i don’t know, so i don’t know how to prevent it from
happening.
it did happen on the film i’m cutting now, and i was able to fix it.
i went though my auto-saved version till i found the last one where
the M/A relationship was intact,
meaning i could Shift-F from a clip in a sequence to the browser.
i did a save as,
then deleted all the edit sequences,
and copy/pasted my current edit sequences back into it.
miraculously, that worked.
(I may have copy/pasted then deleted, i suspect it would be the same)
this was ok or me as we were done shooting, so no new clips had come
into the project,
but the cuts had been changing.
hope that helps,
nick