Why don’t you explain more than, “It sadly doesn’t work for me. It shows that it is processing, but it isn’t actually deleting”?

I would like to help you, but this is nothing I can work with.

Do you have a screenshot? Can you explain the process you followed?

Were you on the Watch Later page? Did you check hundreds of boxes?

Did it say it was deleting any?

Seriously, for all I know, you could be someone who wrote another add-on that does the same thing, and you’re just trying to leave a bad rating.