I packaged my game and managed to make it run. Soon I noticed a problem with booleans located in my custom Game Instance, since their value is not changing. What could be causing the problem?
Okay what’s even more weird is that the Game Instance actually works partly. Like it stores the location of an object between levels if I move it but somehow when I use a boolean in my player controller’s tick event, that doesn’t work at all. I even tried to change the boolean to a switch but there’s no effect.
Did you changed the GameInstance in your Project Settings by any chance? <3
Yes I did, forgot to mention that!
Did you already find a solution? same problem here 
This fixes it (have to rename the instance object in the DefaultEngine.ini project file): https://answers.unrealengine.com/questions/595245/casting-to-game-instance-always-fails-when-packagi.html?sort=oldest
For me the solution was to move Cast To Game Instance nodes
from my character Construction Script
to my character Event Begin Play