[BSHGTO]

Here is your problem in a nut shell. You have broken welds on the AL studs in the front part of the unit in front of the bed slide. This front part is flexing now from the broken welds and the panel is the only thing holding things together until the glue gives up and it starts to crack. It will get worse every time you load and unload from the hitch.
Your Andersen hitch has nothing to do with this problem it`s a camper problem but Keystone will use it to deny the claim. I have included pics of this problem and repair. It is very common and I have found many posts of this issue on other forums. Keystone even has a documented repair procedure for this but most service centers can`t do this complicated and technical type of fix.
So how do I know? I have the same issue as you but my glue joints let go before the panel cracked in front of and in back of the relief cut. This is why you cant find more people with the crack, their glue just lets go first. There are many on Facebook and the Montana forum Borad, Heaartland and others. I am in talks with Keystone now to have the camper returned to them to do the fix properly because I have been turned away from every dealer in my area.
This has been going on since our last outing in January when I first noticed movement in the wall structure when loading. I wil try to get the YouTube video of the movement to post and then the pics. Good luck... we`ll need it.

Watch this video this is the start of the broke studs and your wall panels are trying to hold things together then you get broken glue joints or a crack.

https://www.youtube.com/watch?v=9eJklcjcLWEhttp://

You can see the broken welds on the first pic then you can see the fix on the last.