IOC doesn't work on my P2 anymore, neither CL or HL work when switched on with the S2 switch. I'm hoping that there's something obvious that I'm missing or forgetting to do, and will greatly appreciate help troubleshooting this weird problem.
I have all of the latest firmware and software updates. I've tried basic and advanced IMU calibration, controller calibration, and always calibrate compass before flying. The S2 switch works as far as I can tell (the assitant software shows it responding normally). It's in Naza mode and IOC is checked on the assistant software. I always wait for both sets of rapid green flashes for course and home verification before taking off. I'm flying a P2 (2.0) non-vision that has 2312 motors and v2.1 ESCs, and usually the H3-3d with a gopro 3 silver.

Has this happened to anyone else? What could cause this to happen? How can I fix it?

Thanks for any help you can offer!

When you connect to the assistant and go to the tab for the IOC is the block still checked for IOC function? Need to verify it is still checked or else what you are describing happens if it's not  saved.