Crashing when relinking

So I opened a project from a while back with a small number of files needing relinking - every time I try to relink them FCPX 10.3 crashes!

This happens regardless of whether I locate all, try relinking just one at a time, etc etc

I've had a number of stubborn crashes since the update doing particular actions but usually a good old turn it off and on again bypasses it, this is very frustrating.

Okay, update. It has stopped crashing but when I successfully locate and relink the files it does nothing... there are still warning signs on my events and the media is just black in the timeline. Seems to be mostly compound clips but not exclusively.