I have a buyer who was very rude and trying to haggle on prices after I told them I do not have any interest in working with them. I blocked them. I am still getting a notification each time they message me and it is driving me insane. Of course, it says I can’t reply because they are blocked… Then why can they still message me and I still get a notification and see their nasty messages?
I think you need to report that using customer support.
I don’t know why this is happening but you can try this. On the web version, go to the buyer’s profile. You should see a report link. Click that link and select the SPAM option. This should get rid of them for good.