It sound to me as if the original design was to have an ADF gauge that had a Knob, but then there was an issue with the animation, and rather than fix that issue, they removed the knob, claiming it was now a Fixed card unit – but failed to remove the HDG on the front face.
Personally, I’d like to see the Knob replaced, and the card animation fixed, which is the Plane I purchased in the 1st place, before the bait & switch.