I started a Major Drills Quest in which he asks to play The Slots until you win it. I won a few prizes, but it still doesn't count as completed

That could be the quest where it asks you to win , the specific item

Ohhh, thanks! Feeling so dumb now ><

No worries, it's an easy thing to mistake xD

It seem like Slots is giving out fewer prizes too. I only do 25 tries for Maj Drills. If I don't get the Slots book by then, I give up. Usually I averaged about 4 items. Lately, it has been only one item in 25 spins!

Last time I did an analysis the Slots book has odds of one in forty two. If you usually got it less tries than that you have been lucky.