Yep, me too! It look like Mac really has fouled things up this time.
It seems to me that t is a major bug. Whether I ask for an Apple wallpaper image - a very poor range - and try to get rid of the black/blank screen, it shows my selection correctly in its window, but will not transfer to the Screen.
I then find a roving image.
Reading this page is not good. Apple is nowhere near resolving.
I have two large websites, each followed by 104 countries. So, even if it is only 104 people, I am saying to 104 people, have nothing to do with Apple. I fully understand how glitches can occur, but an inability to repair a glitch - any glitch - means custom and footfall rapidly find other routes.
It is not good to read Apple's recommendation:
you can try a SafeBoot Use safe mode on your Mac - Apple Support will sort many anomalies.
In every case, the respondent is fair and reasonable in their response, and also in their politely informing Apple that the glitch/issue/problem is not fixed.
In this 21st century everyone thinks in terms of "issues" rather than problems. Apple, sidestep the correct-speak and acknowledge the fact that you have a problem that is potentially torpedoing your intenrational client base.
I remember when you were at your zenith, your pinnacle, now, sadly, a very long time ago. You've allowed a gentle glide-descent to become a dive-down.