Damn! Thanks for the feedback
I unlocked the regular map size and, just to test it out, closed the game a few times, through the exit button and by clicking the x button in the window's corner. The regular map did not disappear. When I started a small map and went back to the main menu the regular map was still there. Upon exiting and starting the game again the regular map was locked again.
I hope that helps for debugging. :)