walking through CrashCourse I encounter a strange problem at section 13.3.4, which was send as feedback too. however has one a clue what might have gone wrong? for me it look pretty much the same. (started even at Module-13.mpk and still no clue)
A friend of mine ran into the same problem – open the entity “Shift” and at the top right you will be able to enable various attributes:
Be sure to activate “Store changedBy”. You will no longer get an error :-) It does appear to be a missing step in the course, so it's good that you reported that. Hopefully they can add it to the steps soon!