I used to bicycle along a route where there was a left turn like this, the light wouldn't detect my bicycle. If I sat in the left turn lane on my bike (like I'm supposed to if I'm turning left) and the car behind me stopped a reasonable distance from me the light would never change. This is a street that terminates into the cross street, so there's no one across from us to trigger it, no one going straight to trigger it, and right turners would clear out too fast to trigger it. If I was malicious I could easily have grown a pretty absurd line of cars and buses behind me.

I no longer bike through that intersection (because I don't need to very often, and because I found some nice side streets that happen to take me around it), but I doubt it's changed in the years since.