It's either the program that is corrupted, or the list (kind of a simple database).
Uninstalling and reinstalling shouldn't change anything (let alone delete or empty it) in the list. But, of course, you have a backup of that list, so you can always restore it if it gets damaged. If you don't yet have, better start making it!
But I think it's more likely the list is corrupted. Then, maybe, you've got a good version on some backup. If not, see if it works to export it and import it again. You might need to delete the whole file in between (I assume WLM will make a new empty one if it finds none).
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