I was having the same problems.
I got through all the other freezing problems in the boundary plain, but can't get past this one.
I even started a new game+ and got all the way back there, but now it's freezing in the loading screen before leonis even gets to speak.
I'm going to try a few different things before I give up, I've put too many hours into this game to give up until I know I've exhausted all the options.
I will post back if I find a way around this.