The Gem of Ease could be socketed in some WEAPON (the Gem of Ease can only be socketed in a weapon)… and then you cannot find it with the filter tool… and can be difficult to see. If Urshi can see it on 2 different heroes, then it is definitely in the stash… because it’s the only common place for 2 different heroes.
Try this (from Things That Are NOT Bugs):
- Cannot find Legendary Gem but can upgrade it at Urshi.
…
You can search for the gem by placing a different legendary gem in the top left slot of each stash page then clearing a GR. Note which gem is directly to the left of the missing gem and go to that stash page and the gem is somewhere on that page. If its on an end then its either in your inventory or on your follower.