face keyword not being removed

I have multiple photos that are showing multiple recognized / named faces.

For some photos I want to remove all of the named faces (mostly group photos, keeping the faces with single persons etc).

I select each visible face rectangle in turn and click on the X in the corner and the face rectangle gets removed and the matching keyword is also removed from the keyword panel. 

This works until I get to the very last face on the photo, this last face rectangle goes away but the face keyword stays undeleted in the keywords panel, I need to manually delete the last keyword in the keywords panel.

Why would it work for all the previous deletions but not the last one?

I had my keywords panel closed before I realized why I seemed to keep missing removing these keywords on the photos when reviewing them later.

I restarted Lightroom & PC and tried it with a new catalog with same issue in both.

Using LrC 15.5.1 on Win11