Looks like it was the GCam mod that lets you craft the orbs without thralls. In their Greater Cauldron. I disabled that mod because it broke the icons of most of the epic weapons and armor.
Alchemist bench, you say? My alchemist won’t go on the bench, just goes into the benches inventory. Mod issue, or a bug? In any case, I currently can craft orbs. My witch doctor has been hanging around contributing nothing to the cause.
If you are running them, that may be an interaction between GCam and one of the follower mods (I always took that to mean probably Better Thralls) - certainly there was a known interaction issue that previously (a couple of months back) was affecting being able to use alchemists with certain stations that they should have gone into - I think it was noted somewhere linked from the GCam workshop page (probably in something like a ‘Known Issues’ thread, if memory serves).
Emberlight mod is currently causing the alchemist thrall to not attach to the Alchemy desk. They have it in their known issues post and it should be fixed in their next update.