'Genre' column sort fail

Hello - new to this forum. I'm trying to sort around 5000 files by Genre. Every other column I've tried, it works fine clicking on the column title, within a few seconds. But doing this for Genre just freezes the program - no way out other than to close the prog.

Seems a simple field, less data than a few others which sort fine. Does this point to a corruption in one of the files? Or? Help appreciated.