Request to Dev's. Tune Titan HM.

[Aisukage]

it clearly looked like the player was in while it went off and yet received zero damage when they moved out.

I'm not an expert in this but i believe this is due to the connection to clients and server.

(see enemy move)
Server => Your client

(See other chars move)
their client => Server => your client

so there is all ways going to be a slight delay when it comes to watching other people nothing wrong with connections just the way internet works, which is why it is never a good idea to wait for people to move before you do.