I checked the Windows Store this morning and it showed an update for Mahjong. I installed the update and now am able to play all the games from February.
I don't understand why an announcement wasn't made as soon as this update became available today. I'm glad that the update was there, but it would have been nice to announce it both here and on FB, as had been promised by the mods.
Anyway, thanks to those who worked so hard to fix the problem. It's much appreciated.