Unfortunately, Tiny Death Star has been discontinued, as such if you are unable to workaround the bug/issue by restarting the application or your device, then there's nothing we can do: there is no fix coming from the developers:

The game was removed from the Apple App Store and Google Play Store by Disney in October 2014.

As you are playing on iOS, I would not recommend uninstalling the game if you wish to keep it. Only those who had previously downloaded the game on Android can still redownload & access the game.