Hey !
I'm playing on the witcher 3 on Pc , bought few days ago the pack with the both extensions. I just began the first dlc.
During my trip i began a gwent duel and i find out that i lost all my cards except the card of Nilfgaard deck. In addition I observed that I couldn't choose the North deck., and it was my main deck.
Afetr loading an older savegame I see that I had my cards in all my savegames.
I hope somebody has a solution for this problem.
Regards, Psykomusic

This seems to be an issue for those that used a Gwent mod of any sort previously. Don't know at this point if there is any solution. Those that have tried to just remove all their mods still find their cards missing.

I have never used any mod :/

If you have never used a mod and don't have the console enabler mod - then I would do a fresh install of the game, patch, DLC package and expansions. It's a hassle, but I can't see what else would be causing that issue...

I tried with the 1.12.1 and my cards come back, i'll try a complete restauration.