I believe I have the same problem, in being stuck with the spinning loading wheel.
I’m running the latest wp 3.3.1 and the latest version 1.6.2.
When I try to change the current role to a new one I’ve created, I’m left with the spinning wheel of death.
I think in the past it did work and would just load up the capabilities for the newly created role, but alas now it does not. Any ideas?