When you click to Assign an Item Set, sometimes an incorrect artifact is assigned to the set. When you later try to Equip the same Item Set, the incorrect artifact is equipped. When you uninstall the incorrect artifact, the correct artifact is then shown on the Item Set. However when you then try to Equip that Item Set again with the correct artifact shown, the same incorrect artifact is equipped again.
I’ve attached screenshots of what I just wrote. In the screenshot, the Bow artifact is the incorrect artifact that keeps getting assigned to this particular Item Set.
Device: Apple iPad Air 1
Operating System: iOS 10.3.3
Game Version: 2.4.5 (although the in-game title screen incorrectly shows 2.4.4)