Same issue here. The wishlist feature seems to be completely gone. There’s no button to “Add to wishlist” on product pages either.
“My library” is completely empty for me, though I have purchased items on the marketplace before. Perhaps it is as you say and those creators have not migrated yet.
I REALLY hope this is a bug and not someone who decided there was no need for a wishlist feature. I had 30+ items in there.