hi there.
i had the same problem a few days ago. corrupt clip on unity, trashed the media, erased the MSMs, then couldn’t get the MSMs to rebuild (i paniced a bit here)….so….at the desktop level, i found a Unity media folder that still had it’s MSMs in it, then dragged the media from the OLD folders (the ones you deleted from that don’t have any MSMs) to the folder that does still have it’s databases in it. when i started Avid up again, it scanned the Unity folder that i added the clips to and they all came up online. yay!
hope it helps.
go A’s!
-g-