I'm not certain but I think dragonriding UI is implemented via [bonusbar:5] as in when it shows up and probably needs to be in posses/override or it's own category.

I don’t yet have beta access to test. [bonusbar:5] should be in set already at least.

It didn't work out of the box for me, so I had to modify overridebar='[overridebar][bonusbar:5]1;0' for it to work (in overrideController.lua)

f3be523 fixes it