Screen rotation (Wireless extended destop, WIN10) is displayed incorrectly?

In landscape mode, the display of the 2nd bidisplay (Extended Desktop, WIN10, wireless connection) is normal. Then the display option "Rotate 90°" is activated on the Windows computer. The WMR shows the screen rotated by the PC in full screen, still in landscape format (correct). If the screen is now mechanically rotated to portrait format on the WMR, its display changes: A small window in the center of the screen shows the image of the 2nd screen in landscape format, i.e. in the same position as before.
It was expected that the rotated screen created in the PC would simply remain full screen after the WMR is rotated 90°.
A display in portrait format is so not butzbar. The same PC produces with small displays from other manufacturers without problems representations in portrait format (HDMI in at EIZO and Lenovo)).