Ubook Pro (Win11) not waking from sleep with power button

I’m having a very weird problem with one of my Ubook Pro’s, the one that’s running Windows 11 and is mainly used by my still very young and impatient daughter.

It does not wake up from stand-by when using the power-button (set to standby), but it does wake up when pressing a button on the keyboard (when attached before going into standby of course). So I’m pretty sure the standby/wake-up sequence in Windows isn’t broken.

The button seems to functioning fine in any other case as well. It puts the tablet to sleep as before and when I press it for 10s when in standby (in the not-waking-up scenario) it resets and reboots the tablet just fine. So I’m 99,9% sure the button itself isn’t defective, it just seems to be ignored by Windows when in standby.

I’ve now set it so the tablet never goes to standby (because I can’t wake it up without the keyboard attached) and the power button set to do nothing, since rebooting the tablet 10x a day gets old pretty fast. This does mean I have to remember plugging it into a power-source after every use, as when I forget the battery gets fully depleted and ages much more rapidly.

My other Ubook Pro (still running Windows 10) does not have this problem, so it might be Win11-related. Anybody knows of something else I haven’t tried yet, or had a similar problem? It started behaving like this pretty suddenly, working as intended for months and now not waking from standby for several weeks.