I am on the live branch as of 5/8/2020 I am on the live branch and tracked down similar behavior. I have scanners detecting incoming meteors (sending green) then flipping back to safe (sending red) when the doors are closed. My understanding is they will not send red until the detected meteors are gone. I've attached a screen shot to demonstrate. I have three scanners each connected to filter gate then connected to OR gates. As you can see, the bottom left scanner was sending green (incoming) but now wants to send red again even though the meteors haven't yet hit. This results in cycling the doors unexpectedly and resulting damage.