Problem deleting users with orphaned content/comments

I have tried to delete a few users from a community (11.1.6.14291) and now it seems unable to delete a subset of users, the remaining users have for example commented on blog post which was removed but cannot now be deleted

The error is similar to this 

The member account, userxxxxx, was scheduled to be deleted but an issue prevented the deletion from completing: The blog post with identifier '9f953bee-5174-4791-be51-4d3b3f58ef92' could not be found.

When we check for the blog post with the id it no longer exists, but there are comments linked to it

Is there a way to safely remove these orphaned comments/content?

We have the "Comment Content Cleanup" job running once a day but this doesn't seem to have helped in this case