Add WorldOffset: DIfferent Behaviour in BP / C++

Hi, I would like to move a static Mesh (simple cube) with Add World Offset.
Example:

Here it is moving it as expected. But additionally still the cube follows physics and for example falls down.

When I use in the TickComponent of my C++ Script the very same function, it also moves in X but in this case it hovers still at the same Z where it started:

staticMesh->AddWorldOffset(FVector(DeltaTime*100, 0, 0));

Do I do it wrong, or miss something? WHat is the right behaviour when using the function?

Thanks in advance!