Why are ALL my Mega & ex cards not valid for any kind of deck? Absolute beginner

I want to start building a deck in TCG Live. I have redeemed like 250 codes and got multiple ex and mega cards. I just want to do some AI trainer tests so I can get used to the game.

But every time I try to create a new deck and sort by EX or Mega cards, it shows “0 results.” I know there are some cards that can no longer be used, but I have a ton of EX cards from the most recent Scarlet & Violet sets.

How is it possible that I can’t use a single one of my EX cards for a deck? Every single EX card has a green exclamation mark on it.