There seems to be some weird interaction when using the numpad for movement, coupled with shift-modified commands.
Force melee by using Ctrl+Shift+Numpad does not work with NumLock on.
When in inspection mode (x key), holding shift and using the numpad to move around does not jump tiles when NumLock is on.
This isn't a bug, you have to turn Num Lock off for the engine to receive the proper commands.