When I am above everything and nothing  but sky ahead I start getting " Front optical sensors not operating" warning and it goes in and out, but never noticed it when flying low and there are obstacles around. Just wondering if this is normal.

i have never received that warning except for a few flights in late evening testing the optical sensors.   

i have only seen those errors except in low light conditions.     imo not normal.  

Hi, I'd suggest you to clean the obstacle sensing system and update the firmware and app to the latest.

I've had the same issues as well

nickmedici@bell Posted at 2016-3-31 00:05
I've had the same issues as well

Was it dark or low lighting conditions?