We were experiencing the same issue after we upgraded top 9.18.3.
Solution is to remove user from the offline synchronization in your navigation. To do this you first have to remove all System.User usages from your native application and replace it with Administration.Account, then you are able to remove System.User from the synchronization.
Wow, that is weird behavior. 9.12.2 the retrieve of an object of entityA that is a specialization of entityX still behaves like before. It retrieves the object of entityA
Is your database intact? Check if you still have the object Account with id 10414574138295474. But even if you don’t, still this is very weird. Hope some can explain it.
Did you find a solution? Running into the exact same problem in 9.18.3.
Works fine in 9.12.5 but after the upgrade all my mobile nanoflows retrieve system.users instead of the account.