I have noticed that Hit and Run won't refund MP if anything but the first instance of damage from a Grenade Launcher gets the killing blow. I tested 40mm Frag, HE, and Thermobaric, plus 25mm Frag, HE, and Concussion. I thought initially that mech damage was the problem because all but one grenade first deals heat, but concussion is pure mechanical and DOES function.
Screenshot with multiple combat logs showing the issue:
https://i.imgur.com/WS3dKEf.jpg
