I was stuck in the advanced construction tutorial where one of the steps involved fixing the staging by moving a swivel engine into the same stage as the boosters. However, that's how it already was by default and moving the swivel engine around did nothing. However, after much frustration, clicking the reset button and then adding the swivel engine to the SRB stage did the trick.
KSP2 is already here and there are still bugs in KSP1. In the tutorial no less.
Hope this helps someone out there :)