No guaranty, but I was getting the nil problem after the first attack, and of course this lead to CTD.
May be other problems but this minor fix i did in the Scripts.rvdata2 seems to have allowed me to get past that crash on first fight.
There may be other problems anyway if wish to try it extract this zip of mine, and place the file in your " Main game data folder." allowing it to overwrite your Scripts.rvdata2. ( Back up you Scripts.rvdata2 first to be safe and if does not work you can put it back.)
This was a spacing problem on a variable where they had /// G and it should have been ///G or that is what I found.
If someone else has already fixed this ignore my post. I just did not find where anyone had when searched the thread.