Well the thing is im using the same bulbs in the opposite taillight/brake light and turn signal and they work perfectly fine. Im honestly thinking its a wire or its the connection with the taillight.
similar issue with my 3rd gen 4runner. Recently I replaced the rear bulbs for both my taillights and turn signals and ran into some issues which have been fixed BUT, my left taillight wont work but the brake light that shares the same bulb still works perfectly fine. I dont have a lot of money...