I have just noticed that MDK-ARM V4.22a has been released, only a few weeks after V4.22. The release notes no longer show V4.22 and instead the notes go from V4.21 to V4.22a so it's impossible to tell what changed between V4.22 and V4.22a. All trace of V4.22 has been erased.
I compared the release notes for 4.22 with the new ones for 4.22a - looks the same to me but I didn't compare every processor model to see if something changed.