Hi Wayne Strydom,
Thank you for reaching Microsoft Community and apologies for the inconvenience this has caused you.
Just to make sure: this happens every time you detach the typecover, right? or there are times also that when you detach the typecover, the device is able to detect it and automatically goes to tablet mode? or if you do a re-attach and detach several times, would the device eventually detect it and goes to tablet mode or not at all and you would need to restart the device without the typecover attached for it to go to tablet mode?
Tablet mode in Windows 11 no longer exists as a specific mode. The device should automatically go to tablet mode whenever the typecover is detached. See: Frequently Asked Questions: Windows 11 - Microsoft Community for more details. Considering that a reinstall of Windows were tried already and still issue persists, this seems to be a hardware issue already on the connectors of the device where it is unable to detect that the typecover is being detach and thus, it does not go to tablet mode, but can you please try these steps below first then let me know how it goes:
Detach the typecover (device stays in Desktop mode due to the issue)
Open Device Manager
Click on Action
Select Scan for hardware changes
Check if the device detects that the typecover is detached and goes to tablet mode
Kind regards,
Marrion