I m on my hunter alt and the following issue exists as i post this.
I check the map for world quest rewards and i see a gun ilvl 161.
I fly to the WQ location and recheck the map for the exact location and the gun is now 151 ilvl. After trying relog and going to another area i had it swapping between 151 and 161 and once 148 ilvl.
I also have screenshots of it but not allowed to post them here.
EDIT: When i m at oribos the ilvl becomes 161. When in revendreth it becomes 151(checked the stats they also change).