Sounds like the top cup has been pressed in too hard. Assuming its a ZS top cup, they are quite easy to bend, causing the lip around the edge to roll up, squeezing the bearing. Check out the lip, if the edges appear to be slanted less than about 60 degrees (from horizontal) then you have a problem. Ive seen them collapse from this, so its worth replacing if thats the case… You can also often see that the underside of the lip wont be flush with the frame, it lifts a little. Post a pic if you want a more conclusive diagnostic.
EDIT – Sorry just noticed its a ZS44… Jairaj’s comment on dropping in is wrong in my opinion (sorry dude), the should easily drop in when vertically aligned properly, only if you try and put them in wonky should there be any resistance, and even then its only slight. Ive fitted literally hundreds of ZS44 top assemblies, and none have ever been sticky if clean and inserted straight down.