Camera locks and can't be unlocked

I don't know what triggers this bug, but it's pretty annoying because the only thing I've found that fixes it is completely restarting the game.

Sometimes when playing my camera just locks and can neither be unlocked by the hotkey, nor by clicking the lock/unlock camera icon above the minimap.

This is really annoying, especially if it happens during a multiplayer match.

I've already tried reinstalling the game a few times to no effect; tabbing out of the game and tabbing back in sometimes fixes the problem, but not reliably.

I'm out of ideas at this point; suggestions, anyone?

Click and hold anywhere on the minimap and move your mouse.