Bug? set relative location changes relative rotation as well

I have updated my project from ver 4.11 to 4.16 and this thing just happens without a reason, I am making a first person game where the character has two skeleton meshes components that attached to his sockets of left and right hand when he picks up a weapon the skeleton mesh change to the weapons skeleton mesh and sets relative location to the component, now here is the problem for knows what reason when I set the relative position the rotation or resets or just changes for no reason, sometimes not always just sometimes. Thinking it through there should be something else but the problem that I don’t change the relative rotation of the same components(it happens to both of them) in anywhere at all when I remove the pin to the set relative location everything works fine…