Thanks Marko, I did no know that it behaves that way. I tried selecting some various files, and come that I select do cause the tag window to populate, but others do not. I've included a couple of screenshots showing an empty tag window.
Also, to be clear, I deleted the fields in the tag window myself, while trying to 'force it to reset' mostly because it did not matter what template I chose, none would stick. I figured if I deleted all fields, that might get MC to override a blank window, which did not work.
I expected the tag window to allow me to pick a template and force that template to become the active set of fields in the tag window.
I see now that I have to edit templates to force it to match the content type, which is not at all obvious by the dialog box presented.
So, I guess it's not "broken", but it also doesn't work the way the old window does, which is not obvious, or easy to figure out without 'just knowing' the information you shared, which I did not know previously.