First point is I backup saves and game before to apply a patch. It saved me for saves.
I applied the patch, launch the game, try load a save, see only one autosave. Check in saves folder, only one save left, the autosave.
So on Mac backup your saves and your game before to apply “Miskatonic” patch.
I’ll try with more saves, or eventually for a second launch, and so on.
EDIT: The autosave was the most recent save. Lol I think it’s an ambush I was considering cheat skip. 
EDIT2:
Second CAUTION, when you backup saves, backup a copy of files, don’t move files then copy them back to save folder. There’s another weird bug on Mac, move files or some or options, move the save folder to the new location.
EDIT3:
Second launch, or Launch without Epic (never use it but once after a patch), bugs not repeated after to have restored the save files.
I won’t report anything, eventually a miss click made me let in saves folder, only options and the autosave when I did last saves backup.