I can't get Day 76 to load. The load screen stops spinning and eventually pops up a window that says "Firewatch.exe is not responding". Tried maybe a half dozen times. Even uninstalled and reinstalled, no luck.

Same problem

I got around it by installing the game on another PC, then saving the game as soon as Day 76 finished loading. I loaded that save on my original PC and was able to get it to work. Never did figure out the root cause.

I got around it by saving very often before the freeze.
The game freezed, I reload it and I could load Day 76.

yeah game is unplayable since last patch.