Vaal Gem + Scouring Orb Does not delevel the gem.

I don't know if this is a bug or is it intended, but selling a vaal skill gem + a scouring orb just yields 2 scroll fragments instead of the gem with 1 level less.

Screenshot:

EDIT: Bug reference number is 1924462045

You see that big red word "Corrupted"?

Corrupted items cannot be modified in any way.

Well the vendor is giving me another gem just a level below mine if you want to stay true to the lore...

Also: corrupted items work with other vendor recipes.

And lastly: you can't modify corrupted items...but you can level them up? Why deleveling is different?

Oh well, smartass logic.