When deleting multiple secret keys at once, the certificate list refresh happens now (ususally) before all keys are deleted.
This results in deleted keys still being shown in der certificate list.

Typical case: Deletion of 3 secret keys, after all deletion confirmations the view is refreshed to show 2 of these 3 keys still in the list. But the number still shown may vary.

When you are very slow answering the confirmation questions, the refresh occurs to early even when deleting only one key.