Can´t remove the comments of services

Hello,
I have recently added a few hundred comments focused on services, these have no “expiry date” and I can’t delete them manually, no matter how much I follow the steps of “Select all > Remove comments > remove > Confirm” when I go back to the comments page I find that these have not been deleted.
thanks in advance.

CMK version:2.1
OS version: ubuntu 20.4

2 posts were merged into an existing topic: Not able to delete some comments