Capture Grid 4 stopped working suddenly

Hi, I am using CaptureGrid4 on Ubuntu 18.04. In my setup, I have connected Canon 100D cameras to raspberry pi and raspberry pi to Ubuntu PC using networking. I have been using CG4 until now with no problem but suddenly I can’t capture images now. I can see raspberry pi nodes in the network tab abd cameras connected to the raspberry pis. I mean everything is fine in network tab but in capture tab I can see only one camera. I don’t understand what went wrong so suddenly?

There is one more thing: all the cameras display are turned to black with just a pc icon on screen. I can’t use anything on camera like shutter or menu. Nothing is working and this happens as soon as I start open capture grid on master pc.

Can you check that the license is correctly activated on the main computer?
You can check this in “Help -> About CaptureGRID 4”. The license status should show as “Activated”.

There is one more thing: all the cameras display are turned to black with just a pc icon on screen.

I’m not sure, but this behaviour happens when liveview is enabled from the app - this will disable manual camera controls. So thats the first thing to check.