I have the same problem.
I was running out of space on my ROM drive, so I installed additional drive and moved all my PS2 and OG XBOX ROM's there. Decided that best course of action will be deleting all PS2 and OG XBOX games from Launchbox library and re-import them from new location. Importing PS2 games went smoothly, with no problems. But when trying to import OG XBOX games, there is nothing, list of games to import is ZERO. I tried multiple things inc adding 1-2 games manually deleting and restoring the platform, getting different xiso's and iso's that are confirmed xemu can run... NO DICE. I still can import games for other platforms, and I have no problem at all. It seems that only OG XBOX have this problem.
Did Dev's acknowledged the problem?
~romeo01