Herald of Ash - not upgradable

I have Herald of Ash at level V and can't find it to upgrade it to VI. It literally isn't in the list. I tried turning it off, removing it, etc. I Tried "all gems" and looking for it manually, doing a search, etc.

It won't populate in the list for upgrade.

I don't know if it's because I don't have the stats to support the upgrade or something, but you'd think that would make the gem grayed out or something, but still on the list.