Having a small easy to miss patch breaking achievements without any warning is a really bad idea tbh. At the very least there should be a popup warning about incompatible version when starting the game (one does not seem to show if you just click to continue the current game). I'm pretty sure quite a few people lost their saves since it's easy to miss that the Achievement was icon suddenly greyed out.
Also, at least for me reverting to previous version doesn't even seem to work this time, previously I haven't had any issues with it (using the 30.4 save, not one modified by the 30.5 version). Not sure if other that's a common issue though or just some weird glitch.