I last played at my survival world on version 20w46a and the frost walker effect seemed to be working fine, but in 20w48a the ice didn't start to break (I was using golden boots with frost walker 1). If this was an intentional feature, I'm sorry for the interruption.
Linked issues
duplicates 1
Comments 2
Frosted ice requires light to break, see MC-98903
Was it at night? If so, frost walker ice doesn't melt at night for some reason.