confirmed the bug with the save.
I guess it definitely has something to do with the reactionmelee. And with loading a save. Here is an example below that verifies that reaction shots at melee range are definitely possible without a freeze - while i also confirmed that the reaction shot from loading a save freezes the game. I guess this is yet another example of what goes wrong when you load a save.
It might help or not but the most stable saves are manuell ones. manuell > auto > quicksave.