I can’t find my Enforcer gem. It’s gone, but i can see it when I’ve completed a GR and able to upgrade but its totally gone on all my characters.
And a new one doesn’t drop.
What can I do? I’ve tried everything I could find possible in the forum, but it gotta be a bug.
It’s probably in a ring or amulet in your inventory/stash
If Urshi can’t upgrade the gem, it is not missing. Not a bug:
Use the search inventory function.
Unfortunately, that won’t work if the gem is socketed in some piece of jewelry… a limitation that was pointed out to Blizzard in Season 16 PTR and which has yet to be fixed by Blizzard…
Look at the rings and amulets in your stash. It’s there, you’re just overlooking it.
Check your followers as well 
As Mask pointed out, if Urshi can see it, its not missing and it exists. THis is true in EVERY case. Use the method that Mask linked to find what page its on. And please search as this has been asked before.
According to eriksson’s Profile, none of the Followers have it equipped. That’s why the players above suggested using Stash Search.
And, as Boubou pointed out, Search won’t work with Gems inserted in items.
Therefore, if Search does not produce a result, manually look at each socketed piece of Jewelry in your Stash, if your Inventory is empty.