All my turn signals work when I try them with the switch: left and right. But when I press the hazard switch just the rear driver side blinker is not working.
IF it were a bad bulb... wouldn't one of the turn signals also not be working when the directional arm is moved much the same as when the Hazards switch is enabled; they use the same bulbs and elements.
Inspect the Multi Function Switch, harness wiring and connectors inside the steering column for loose or melted wiring/harness connectors.
You can remove the two plastic clam shells to do the inspection; IIRC there are three screws to remove.
Turn signal and brake, and hazard on the same element? Then the running light is on the other element? Yep after thinking a little more it won’t be the bulb. Guess I was just about asleep when I posted.