Optical flow unable to initialize camera


I am using some Intel aero RTF drones with Lidar Lite v3 from Garmin. I want to use optical flow in them, I configured the parameters EKF2_AID_MASK to 3 and EKF2_HGT_MODE to 2 (range sensor). For any reason, some drones accept the optical flow and others does not. It is also frustrating that one of them worked well one day and failed a few days later. The cause for failing is said to be “unable to initialize camera”. I believe this is the down facing camera, but I don’t know how to access this camera to check if it is working.
Did anyone have this problem before and was able to solve it?

Thank you for your help.
Juan Heredia