FCPX has always been a bit finicky about burning optical media for me, but now with FCPX 10.3 it seems that blu-rays are getting stuck at 80%. No error message, no "Application not responding", it just gets to 80% and doesn't seem to go anywhere else. I'm on a Macbook Pro, FCPX 10.3 and using a USB disc burner. It's been at 80% for 7 hours. Has anyone else had this issue?