User who blocked me popping up

The dms of two users who have blocked me keep popping to the top of my dm list. This is not a server. As far as I am aware we no longer have any servers in common. I am still blocked as far as I am aware as I can still not message them. After a while it will go back to the correct spot in the dm list according to time since last messaged. Is there a way to stop this? It's painful to see.