Same behavior here with update / build FP6.QREL.15.176.0.
Sometimes pushing up turns on the light. Sometimes pushing down turns it on. Sometimes nothing happens when pushing the button up/down.
Same problem here:
- Moments button + flashlight = chaos
- https://www.reddit.com/r/fairphone/comments/1oolbyy/using_the_physical_switch_for_the_torch_is/
This may be a fix worth testing. (unfortunately I can’t test it soon, because my aunt has the FP6 and I’m still sustainably using my FP3 
)
The fairphone moments switch doesn't work - #7 by urs_lesse &
Is FP support around here or has someone already notified them?