We are aware of this issue and our developers are working on resolving it.
Meanwhile, we suggest using the following work-around:
Go to your system settings and under your Apple ID
click on Sign-In & Security;
click on 'Sign in with your Apple ID';
go to Disney Dreamlight Valley and click 'Stop Using Apple ID';
Then, reopen your game. It will prompt you to sign back in with your Apple ID and it should resolve the problem.