I wonder if it's due to multiple devices being used. I use iPad and PC and although PC is by far the most used, I have changed between the two, and so I wonder if I completed a couple of quests on the iPad and that's why they're no longer synced properly.
For those who are experiencing issues here, are you using multiple devices to play Gwent?
For those who are experiencing issues here, are you using multiple devices to play Gwent?