Actually, could you try running it again? I think I fixed it by brute forcing a solution :)
Viewing post in Gravity Inc. jam comments
Yes it works now. I also understood why I couldn't change gravity when had fuel. The red blocks don't allow to change gravity when you are in them. But it isn't obvious because you also used them as decoration... You shouldn't use it as decoration or you should emphasize it somewere in gameplay for example text label