I got above message from my Phantom 4 when trying ActiveTrack which currently can't be utilized. Tried slowly flying toward object and no warnings so no obstacle sensing. Good ambient lighting present. Sensing is enabled in DJIGO and ActiveTrack did work previously. Have not had any hard landings or mistreatment. On vacation and currently no access to PC to upgrade firmware. DJIGO does not report any error at startup nor instruct me to recalibrate sensors. Any thoughts/help would be much appreciated. Thanks in advance.