Repro steps on iOS:
- Open game
- Login by Facebook
- Facebook login was successful: True
- AuthToken is valid
- Close game
- Open game
- Login by Facebook
- Facebook login was successful? - Already had token!
- AuthToken is empty!!!
FIX:
In Runtime/Online/OnlineSubsystemFacebook/Private/IOS/OnlineIdentityFacebook.cpp in line 141 add following code:
FString Token([accessToken tokenString]);
UserAccount->AuthTicket = Token;
GConfig->SetString(TEXT("OnlineSubsystemFacebook.Login"), TEXT("AuthToken"), *Token, GEngineIni);
Cheers!