I'm not sure, but I don't think I was in VNAV, I only engaged AP and set AP NAV to FMS. I did some FLC, but always controlled the throttle manually during the whole flight. After the issue, the throttles were at 0 and didn't change at all (I saw the values on the data output overlay, always at 0), even the keyboard command "throttle up a bit" didn't do anything to the throttle value. I disconnected all servos, but couldn't change throttle even then.