I had some issues with this as well. I just started mine today, ran it for two hours with no cards. I went into the settings and changed it to idle one game at a time. Within 15 minutes I had one card!

Yeah, it seems simultaneous idling isn't working anymore. Just idle one game at a time.

Simultaneous idling was mainly for the 2 hour wait time for the refund policy. It made it so you can idle 30 games at once for those 2 hours rather than have to do it over 60 hours individually. Idling multiple games at the same time always took way longer for drops than doing it one at a time because it doens't run them all separately like you are running 20 different versions of Steam at once. They are all fighting each other for card drop time.

引用自 Bakugo：

Yeah, it seems simultaneous idling isn't working anymore. Just idle one game at a time.

Even when idling one game at a time I think i've only gotten one drop and it took hours