I got the email today (Sep 1st) about self-hosted region fees, which is as it should be. The region fees page however, despite listing -0,10 as balance, still had the "There are currently no fees to pay!" text.
Also, why 0,10 instead of 1,50? The region currently has only the terrain set up, so is it based on the fact there are ~0 (there might be one or two) objects?
Payment itself went through fine and now shows positive balance as it should.