Is it a humidity or lack of humidity issue? I had some cards that warped pretty bad when playing on an enclosed porch when it was raining out. They went back to normal when brought into safety. But now I'm encountering this with other cards inside too. Do you leave games set up for a while? I ask because I tend to leave things set up for days on solo games, taking turns when I can, and that is when I start having this same issue. Maybe a small dehumidifier nearby? Thinking of trying that myself.
We leave the game set up in the basement and trying a small dehumidifier got no results (as in, it collected nothing). I haven't heard of lack of humidity as a problem before...