After synchronizing my cards with the app server, I have 68 due cards on the iPad and 86 on the iPhone.
When the number was different for the first time, I simply asked the due on the iPhone and then there were 0 due cards on both devices and everything seemed to be ok.
This morning I had a difference again. I deleted the app on my iPhone, reinstalled it and then synchronized it again.
The difference between the cards due has remained.
What can I do now?