HDG knob did not work for me with version 2102.1b. HDG bug also does not work without this mod.
I also had the WT G1000 mod installed, so I removed that, but none of the HDG knobs work. I don’t know when this happened, and this is further complicated by the fact I have a lot of external hardware for interacting with these objects, and hardly touch the in-sim cockpit at all. It could have been broken before the December patch for all I know.
This post suggest the HDG knob issue has been around for quite some time: