I have the same libraries on my internal and external drives. When i open all projects in fcpx they're present but aren't linked. When i go to link them from either drive i get the following:
Incompatible File
1 name matches were found, but one file is not compatible.
Relinked files must have the same media type and similar audio channels as the original files, and must be long enough to cover all the clips that reference the files.
Select a single item at a time to get information about why it is not compatible.
I haven't been in fcpx on this computer to open a project in a month or so. I was able to open projects previously. During that time my HDD has gotten full and my computer has turned off or crashed it seemed because it couldn't handle all of the activity with such low HDD space. That's the only thing of significance that's happened since i was able to open projects in fcpx. I was copying and pasting the libraries to the external to free up space on internal.
Any ideas? joe