I am on PC and the grinder crashes my game. I’ve noticed it does this when I try to grind purples and there is a 90 moonstone grind option.
There is currently a bug with grinding 3 purples. It doesn’t happen all the time and it only happens with 3 purples. I read somewhere that when they released Lady Hammerlock a bug slipped through bypassing the hotfix they did fixing this issue and that they are working on a permanent patch to fix it. So when grinding 3 purples do so at your own risk for now and you might want to save before doing so.