Axis bomber boys healing foes?

I've noticed that my axis bomber boys, whenever the death mark skill strikes, the following perfect strike does NOT damage more - on the contrary! My enemies actually HEAL!!

So I am forced to go for GOOD or LATE hits, in order to avoid this from happening. On bosses, they heal a HUGE amount of HP - it's ridiculous!

Am I the only one with this issue or am I missing something?

It happens sometimes. I don't get it a lot but it's a problem. I really don't know what to say, I've found a way to bypass that bug but I don't know how LOL

Sounds crazy, try different kind of attacks, physical, magic, true damage. I think one of those prevents this bug.