no "CORRUPT" prompt for skill gems at corruption altars

in campaign or and in T3 temple, i get the prompt to corrupt equipment but not gems.

ref# 4190952907

Are you talking about from the same room? I.e. "Locus of Corruption"?

Because the Locus doesn't work on Gems. You need Doryani's Institute for that.

The corruption altar in act 2 should now work on gems, it was in the patch notes. But it was broken for gems before the recent patch. I didn't test it myself to see if it was actually fixed, since that would require running a character to act 2.