@VOXL-Flight What happens when you restart camera-server?
systemctl restart voxl-camera-server
Are all the camera cables in good condition? Intact wires?
You may also want to re-configuring mpa:
voxl-configure-mpa -p -f seeker -b blue -c 7 --fc yes
If it comes down to it, you can flash the Voxl with a system image & Voxl-suite.
Select wipe & you'll start with a clean slate. Instructions can be found here
*After flashing you will need to calibrate the cameras, both stereo & tracking: here