Originally Posted by Iride01

Take the fork out and put the stem back on the steerer tube and tighten the bolt for the compression plug and see if it's bulging your steerer tube as you tighten it. Might be that it bulges so much that it's rubbing the head tube or bearing races somewhere.

Might can just run some calipers down the tube and see if the area around the compression plug is a wider diameter than the rest of the steerer.