Bug with middle mouse camera drag

I’m having an issue whenever I press the middle mouse button to drag the camera. When this happens, most of my keyboard buttons become unresponsive. So if I’m dragging the camera, I can’t give my units any commands, or create/select control groups. This issue is specific to Warcraft 3, as my mouse and keyboard work perfectly fine in other games and outside of the game.
I tried using a different mouse, and I’ve also tried resetting all settings to default, but that didn’t help either.
As far as I could find, this issue is specific to the middle mouse button. Any other combination of button presses work fine.
Has anyone else encountered the same issue? I rely heavily on middle mouse dragging for camera movement, so the game feels unplayable for me right now.