I guess this happens in most of my posts, feel free to close or delete it if still non-clear after this reply.
in our forum there were previously some tag groups, each allowed in only one of the categories.
recently we have decided to remove the limit and allow users to tag topics in each category with any tag that make sense. [so all tags were available for any category].
when we removed the limit in the category setting, tags were not shown in the tag-list dropdown of composer anymore! i.e. here:
tags only appear in the composer, if we delete all the tag groups in the tag page.
as an admin user, this behavior was not expected and I was feeling dizzy for a while to find out which setting to change in order to get all the tags back into the list.
p.s.: I’m just trying to report a user experience! that’s it.