I have a tag stage-2 that cannot be added to topics anymore. Here is a screenshot of my /tags page:
I want to add the tag stage-2 to a post, but I get “No matches found” instead of the normal “Create Tag”. I tried removing it and re-adding it to the tag group that it was originally on, but got the same “No matches found” message when I tried to add stage-2 back to it.
Noting for posterity that we were able to resolve this. There is an underlying issue where a tag can become “trapped” behind the allow_staff_to_tag_pms site setting if the the tag was only applied to PMs before that setting was disabled.
The workaround until there is a fix is to re-enable the setting and either remove the tag from any PMs, or you can just add it to a normal topic before disabling the setting again.