Get the tube ASAP! ( the elevators seems to be the main bug causer )
Do NOT speed up or pause the game! ( this also helped avoiding bugs )
If the game appears to be frozen, freeze and unfreeze at the top of your building. this should make the floors reappear. Now place a new floor and the game should unfreeze.
Make sure you always have at least 2.5k for this to work!
+ if it helped
Get the tube ASAP! ( the elevators seems to be the main bug causer )
Do NOT speed up or pause the game! ( this also helped avoiding bugs )
+ if it helped