After July 29 2019, 4 of my 5 Arlo pro and pro2 cameras indicate ‘This Arlo device is offline.’ 3 cameras had been plugged in and 2 on battery. One on battery indicates ‘Time to charge your battery’ even after charging battery, probably because it’s offline. 1 camera continues to work properly so it is not a network or base station problem. I reinserted battery with no change. I deleted one device and now cannot add it back in. After pressing and releasing sync button the blue light flashes but the device is not discovered.
I had to remove the USB backup devices completely out of the base for it to stop going offline and only then could I get the cameras to resync.
I have not removed backup storage device.