No, nobody seems to know where the problem lies. The only people who succeeded in using their bluetooth keyboard with firmware PR1.1 have upgraded their firmware OTA and not by reflashing via USB. It looks like this is the only scenario to get the bluetooth keyboards working in firmware PR1.1.

What difference in terms of the bluetooth stack and configuration files occur with a firmware upgrade OTA vs USB?
If we can pin this down, maybe we can find and fix the problem.