Yes I know there are existing items that are broken still from the upgrade that are still being worked on, but this one needed to be put somewhere it could actually be gotten to since it was buried in the depths of template code instead of something actually controlled somewhere one could find...
Working Feature No One Can Get To > Feature That Can Be Accessed But Stopped Working Temporarily
So you can now choose your maximum signature height via the Market.
Existing sizes from previous group settings have been ported over.
You can confirm how large yours is from the bottom of the Edit Signature screen in Settings.
Also, unrelated, PM expansions are working properly again as of yesterday.