Like so many others with problems recently, I just upgraded to 2.2. I can't delete a comment from the Comments tab. I have to go to Edit in each individual comment to do so.
Here are screenshots of what happens when I try to delete straight from the Comment tab:
It goes through the normal red fading as if it were actually deleting the comment, then it goes to this:
Then it just stays stuck on that last screenshot and upon refreshing the page, the comment shows up again just like the "Before Deleting" screenshot.