This problem is more interesting after a bunch of testing.
If you reboot after this happens, all is well.
If you quit FMP14 when this is happening, and open the same files again, cut and paste is fine.
If you create a new file and add a text field (for testing), while this is happening in another open file, and come back, cut and paste works fine.
While it is happening, cut and paste works fine into other programs (Contacts, Calendar, Reminders, Notes).
El Capitan Disk Utility checks out fine.
So, we're not sure what to make of all of this.
At this point, we'll keep trying to isolate some factor common factor. This was not file related as we had three of our files open at the time.
If it is a bug, I'm not sure it is FMP14 or El Capitan.