[retiredbiker]

On Ubuntu 20.04, Calibre 6.1

If you type a comma to try and add a new tag, all you get is the popup list of existing tags. The field won't accept any letters.

If you start typing letters without the comma, it will take them as added letters to the existing tag. If you empty the field and try to add a new tag, you just get the list again.

In the image, I typed ", d". It dis not add "d" to the field, only brought up the "d" section of the list.

EDIT: Tried the Publisher field, and it does the same thing.