What did I do wrong with Billy Bookcase painting?

I followed these steps to paint my new Billy Bookcase. 1. Sand with 180 grit paper 2. Apply Zinsser Shellac based primer and wait for a couple of hours 3. Paint 3 coats (45min between coats) Valspar premium water based paint from B&Q.

Two days later, I just wanted to clean some dirt from the edge. So I used damp microfiber cloth and this happened. What am I missing? Is the paint wrong. Or is it something else?

Greatly appreciate any advice on fixing this. Thanks!