@Skenku: Ok, trying to keep all your modifications in my head to figure out what might have gone wrong is quite tricky, but I’ll try. I don’t see any reason why your top code should allow for displaying all tiles in range instead of just pawns that can be targeted. In the base toolkit, the Find Tiles In Range function for the player is set up so that “find only pawns” is set to false if current move is 0. Have you modified that stuff in the Activate Unit part of ATBTT_PlayerController?
I can’t see a reason why Recieve Damage should not be called from the screenshots you’ve posted. I guess the attacker might be attacking an array index that does not hold a pawn? You could try to print the index of the tile the attacker is attacking and the index of the tile the target is standing on and see if they always match up. I usually fill my blueprint graphs with Print Strings when I run into these sorts of problems.
@xiuxiu: Thanks, glad you like it 
I assume you’re using your own custom static meshes for tiles? The easiest way to fix your problem is to make sure the pivot point of your static mesh (set up in whatever modeling sotware you are using) is at the top and center of your mesh. I did this with my own meshes as I thought it made sense that the “floor” of the grid was at the same Z location as the Z location of the grid, and so I would not have to correct for the height of the meshes in blueprint. I assume the pivot points of your meshes are in the center of your tiles, since you have to add half their tile bounds.