Steps to reproduce: 

Have your current mission be 500, 000 damage to the Demon Lord.

Fight the Demon Lord and deal in excess of 500k damage. The mission will not be completed, and progress won't be made.

Android 13.

This totally blocks progression. 

EDIT: I accidentally attacked him on the highest difficulty. Is it now stuck on tracking that difficulty? I've been trying to kill the Easy one for a couple days now.

EDIT 2: yup. That's the problem. I can only get points on nightmare. I can only do 15k damage to nightmare, so should I just quit Raid or can this mission be reset on my account?