Since the last update XMM8 quickly shows how many movie files are missing (bottom left) but doesn't say which ones they are as it used to. It just displays the clockwise-spinning spots in the middle...I've left it for ages to see if it was just processing information but it really does just seem stuck....
All my drives are internal and always connected so it can't be just that.
I found a workaround though which doesn't take too much longer. If you go to Tools>File Manager (Movies)and tick "Check for Missing Files in real time" at the bottom and then just wait you can scroll down your list of movies and the missing ones will show up in red.