Halo Wars DE Steam Version Camera Drifts by itself

Doesn’t happen in normal gameplay, but only when using the MAC Cannon or Unit Pickup on Mission 6. Haven’t tried other missions yet, but I can’t select a pickup/drop off or use the Mac Cannon because as soon as I click the camera zooms off in one direction.

Does anyone know of a fix?

I’ve tried restarting the mission, the game and even turned off in game overlay for Steam and it still doesn’t seem to work. Wanted to play it again to finally beat it on Legendary, but it’s making it impossible to beat the mission.