Thanks for the long and detailed reply.

"Assigning cursor keys in addition to WASD, then trying to move diagonally with up/right/down/left works perfectly for me."
Surprising. I double-checked the keybinds—there’s no arrow keys assigned anywhere.

"and my right hand on the right half of the ...

Maybe someone had the same problem and found a fix, because right now I'm losing the will to play. Normally, you move around using W A S D – and that works for me too, but I’m left-handed and I’ve always used the arrow keys (up, left, right, down). Left hand on the mouse, right hand on the arrows ...