[Fuchs]

I found this Reddit post particularly helpful when I had the exact issue. It seems to be common and drivers side specific. No such thing as a unique problem when you consult the internet.

Wanted to leave a note in case anyone else is dealing with this issue now, or in the future.
My front left turn signal would sporadically stop working when it was warm out, and once winter hit, it fully quit. I figured it was a bulb and bought a set of four to replace them all at once. After replacement the front left was still not working. This led me through a series of forum posts that lead me to believe this is a common issue on our cars, but I hadn't heard of it before.
The fix was very straightforward, after removing the headlight from the car's body you pop out the bulb holder. On that bulb holder there are two metal contacts that stick out from the edges, these make contact with the metal inside the headlight housing. I noticed on my bulb holder that one side was pushed in further than the other. By pulling on that contact with a needle nose pliers it came back out to the same depth as the other side. Some forum posts suggested dielectric grease, but since I didn't have any on hand, I tried just plugging the bulb back in with that contact pulled out.
This fixed the issue!
I retried my old bulb and sure enough it wasn't even broken, the contact must've just shrunk into the housing over time / with temperature change.
I personally head to Reddit before other forums, and even though this info is available on places like Rennlist, I couldn't find it on here. So I figured I'd throw this out there for you guys in case anyone else comes here first when looking for fixes!