On the level with the marching band after completing the objective and pressing the key to go to the next level I don't get sent to the next level instead I get sent to the single-player menu.

The level also isn't unlocked in the level select.
I've tried changing the key bind which had no effect on the results.
I have replayed the level in its entirety a few times with the result being the same.

Side note: The save system also doesn't seem to work with loading a save making me restart the level rather than continuing from where I left off in the level.