I’m only doing a couple of things different than you, not sure if this would make a difference?
I don’t plug any of my equipment in until after my StellarMate is powered up and booted.
I’m running Kstars on my Mac and connecting to the StellarMate over WiFi.
Are you letting everything update to the latest version before trying the camera? Doe you have the camera plugged into the 12v supply. I don’t think this would have any impact but I’ve always had my camera powered with the 12v supply.