Unable to use USB display as primary

[AlbanRampon]

Hello,

I have a few questions to be able to understand what you have.
Can you tell me which graphics card you have and which driver version?
You can also use our customer support tool after you've reconnected the other monitor so I can look into the logs. If you activate advanced logging, I can see what happened during the Asus USB monitor only period (connect HDMI, activate the logging, disconnect HDMI wait 30s, reconnect HDMI, deactivate logging and gather logs)

I believe you have a ghost monitor somewhere still present and that monitor is the primary.
If you right click on the desktop and then select Display settings, can you use the Win+Shift+Right Arrow key to move the window to the Asus MB168+ ?

Kind regards,
Alban