2012 XC60 Brake Light Out (not bulb) Please Read

[SwedishcarsRweird]

As the title states, i recently bought a 2012 XC60 t6 for my wife to daily drive. Recently we got a brake light bulb error on the dash so I went to swap bulbs only to find that the bulb is not the issue. I had previously installed LED bulbs in the brake lights for brightness/longevity but the left rear stopped working.

things i have done so far:
swapped bulb with right brake light which was working, did not resolve issue
checked bub for polarity due to being LED, did not work in either orientation
replaced left brake light bulb with standard filament bulb, also swapped right side to standard bulb as well to rule out low current draw possibility sometimes associated with LED bulbs, did not resolve issue
checked fuse #22 (5a) in fuse box B under glovebox, found to be in working order
tested wiring on both sides with a multimeter, right reads slightly above 12v, left is reading slightly less than 6v at the connector

I have looked over the wiring and did not identify any physical damage to wiring or connectors.

any suggested course of action from here other than taking to the dealership? Is there a relay or some other common issue to check?

would like to resolve this soon and am willing to do the work myself with suggested items to check. I’ve had many VWs, Audis, and other cars with crap wiring over the years but never seen an issue like this before.

i have also done some online searching but havent identified anything that seems to be relevant to this model specifically.

[RickHaleParker]

Is there corrosion or tarnish in the lamp socket?
Try cleaning the connectors in and to the lamp socket. It does not take much to create a high resistance.