Jules, I'm afraid to say that not all issues with radio group buttons have been completely fixed yet...
While the issue I described above has been fixed, I've discovered a new beahviour that's causing problems for me, to do with at what point the internal state of a toggle button is being turned off.
In my app when I click on a radio group button, within my buttonClicked() function I'm checking the toggleState of each of the button in the radio group. Previously when I was on v2.1.1 the toggleState of the previously selected button would be equal to false by the time buttonClicked() was called, but now on the latest code it still seems to equal true. So it seems like the internal state of the previously selected button is set to false after buttonClicked() is called, instead of before as previously.
Thoughts? Was this a change you wanted?