I am having a problem with deleting unwanted card attachments and checklists. After following the steps of deleting them they are gone from the card, but if I click out of the card and click back in the previously deleted attachment or checklist is back. They won't ever permanently delete. I have tried this over and over again for years and they always come back. The only way I have found for me to do it is completely start over with a new card.
