I have 2 saves which occured after some point which cannot load the geoscape, it gets to the view of the globe with some ui functionality remaining (like mouse over of havens stills pops up the circle). But that is it, no main UI loads.
I say “after cetain events” because I don’t know what it is, but it is two different saves down one game play branch that have this happening. Between the two saves, I loaded and completed a mission. So it seems like the thing which broke it occurred during the geoscape phase. The event which seems to corrupt the game doesn’t prevent it from running, only from loading the geoscape, apparently.
Needless to say, in that state the game is unplayable.