There's a hole in your graph in the am. Not sure if the huge gap is another hole. If the cerbo is plugged into the batteries and they went below 7v or whatever the cerbogx min voltage is then it'll shutdown. When solar came back on and charged batteries it'll bring that back on. But the inverter low voltage shutdown is higher than the cerbogx min voltage so the batteries likely would have to be off/dead. You could check the logs or any other graph and see if data throughout that time or not.
I'm not certain if that's even normal but it works for mine because it's having some issue. Just last week I was driving and shut off my inverter on the cerbo on accident meaning to switch to inverter only. It needed manual restart. Tried just restarting the cerbo while driving a few times but wasn't down enough. Had to pull over and pull that cable for a second.