Not recognising monitor if not already connected at boot

I have a monitor that I share between 2 computers, this means that sometimes when I boot my Manjaro PC, it is not connected to the monitor yet. I expect that when I change my monitor input to my Manjaro PC, that I would see the Manjaro login screen, but I don’t; I get a blank screen, in fact, my monitor doesn’t even think it is connected to anything. The only way I can fix this is to hard power down and reboot, now the monitor is connected.

I don’t know if it has any baring on things but I am running an Nvidia RTX3090 with proprietary drivers and the connection is DisplayPort.

Did you ever find a solution? I have the same issue, but with an older Intel Graphics card. It just happens sometimes, most of the time it works. It might be connected to DisplayPort, as it usually happens with that monitor.