Item states that it will upgrade a conduit up to ilvl 226. When I us it, it states “You have fully upgraded all of your conduits to your current specialization”, however I still have a general conduit that’s ilvl 213. I’m a demon hunter and the conduit is “adaptive armor fragment”.
There have been other bug reports that this particular conduit is impossible to upgrade because it’s not associated with a specific spec.
I don’t recall seeing any workaround.