On my old 15, my left switch pack would not activate the cruise control, everything else was fine. I had to change the switch pack to correct the issue. So that is possible for something like that to happen. I assume it worked for a bit after the bar install? Just for the heck of it, I would take a look at your settings in the infotainment center to ensure all settings are correct. If it did not work right after the bar install, not sure as you have double checked wiring. Hopefully others can give better input.
Also, welcome to the forum.
2018 FLTRXS, Vivid Black, KW Slicer Front Fender, Sundowner Seat/Modified by Mean City Cycle