Deleting tags to Unassigned Tag Bug?

Just started tidying up this complex autocad / sketchup hybrid content file
Setup my own simple tag structure and
started moving content into those tags
tried to reassign all the other tags to unassigned (layer 0)
but I do not get that option anymore … is this a bug ? or did someone change the process?

Cannot assign to unassigned ? [layer 0] it is not listed
Does delete mean delete the tags or the content ?

not brave enough to hit the second option…

PS. I am trying to get rid of all that exploded autocad linework and disorganized layer structure

That looks like the issue that has been talked about in another thread where you can’t scroll the dropdown list, it is being looked at.

thanks Box, did a search… didnt see that thread !