I'm not able to make it working, even after tons of reinstalls and hours of tries.

So is it possible to download previous version, that gives zero problems to me?

Same problem as OP for me, and I'm 99% sure there is a bug.

I updated Steam idler in computer A; Norton gave me an alert about security; no card drops for 3 hours.

I started computer B, I didn't update Steam idler, got card drops as usual (same game as before)