Yes! Naturally this was on copies of copies of copies. The original media lives untouched in a temperature-controlled vault with Imperial Guards stationed 12-deep in front of the door. Don’t mess with your original media kids!
I went through and changed the start timecode in the Contents/Clip/*******.xml files for all 70 of the clips I wanted to span, and now FCP joins them up with no problem. This saves a lot of importing and exporting time. When you’re looking at over 650 GB to copy back and forth, the time really adds up.