I ranted some time ago that FCPX dos not make it easy to find what's missing in the Timeline when the only thing that shows is a lame red rectangle with a yellow exclamation point.
Apple has one for missing Files - Well OK, this one works, and the remedy is to relink:
But then it has this one for Effects:
And one this for Titles:
Great! But what is REALLY MISSING you ask? And there is no way to know until you click on the clip and look into the Inspector to see what can be identified there. Not much.
In this case I was missing an Adjustment Layer and the Apply Basic LUT from Coremelt. This makes troubleshooting difficult.
On the other hand, someone (Denver Riddle at CGC) has been paying attention:
Now this is useful! As it is telling you exactly what's missing!
Now I notice this "feature" is not coming from Apple, it's coming from the plug-in developer, but hey, it's proof that it's possible to flash something useful. Thank you!