17.1 Pro Dual monitor setup problem

I'm using a dual monitor setup on a nvidia RTX4070. One is a MSI 34" and the other a AOC 27" in portrait mode. Original after installing ZorinOS 17.1 everything worked perfectly. After one of the last minor updates the system having problems.

Frist the AOC screen didn't suddenly work after rebooting. After a lot of trying around I managed to get it to display something again. However in the settings it is positioned to the right of the main screen. When I try to move it to the left the display doesn't work right any more.

Also since the problems began the screen often turns black for 2-3 seconds when staring an application.

Last but not least on login the screen to enter the password is displayed on the portrait mode AOC screen and a small portion of the left of the main screen is showing the grayish wallpaper.

Is there a way to completely reset the displays? Anyone got a hint where to look to fix this?

Thx