Two things you must have for a bulb to work is power and ground. Your problem lies therein, and since one assembly works on both sides it sounds like you have a socket problem.

"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.