During battles, as soon as I hit "Finish deployment" my camera starts drifting to the right and doesn't stop until it hits the far side of the battle region "box". I can move the camera normally with the mouse and keyboard, but as soon as my input stops the drift resumes. I'm (no longer reasonably sure) that this is not because of stuck keys or other input devices. Any pointers or advice?

Edit: looks like it triggers on KB input not "as soon as" I enter battle. Sometimes stops, maybe after hitting the corresponding key (d) a couple of times. Nothing systematic so I'm leaving this open but maybe hardware-related after all.