The profile changes after commit 2d8ab114d866608c11fe427783847d49f07ee435 caused weird behavior in my setup. It is a laptop with external monitor via HDMI. That monitor is supposed to be the primary display as long as it is connected. The monitor is on the "right" side, the laptop on the "left" side. Both have the same resolution, but different size. What happend after ugprading to f2e5888137bd696b85c6feae81d35b9e83b3a62c is that everything had to be redone. See bug#15272 for this particular bug. I selected the monitor as primary, it was already placed on the "right" side, I disabled screen mirroring. Then the display-settings window disapeared from the main monitor, it had to be dragged from the left screen to the right screen. To my surprise, the content on the left screen did not change at all. It remained a static picture. Application windows that did appear initially on that "left" side had to be moved manually via 'Alt+Space'+v and the cursor keys. The main cursor is always shown, that 'dragging cursor' was also shown during movement. Initially I reverted the package from master back to 2d8ab114d866 to get a working system. Here the previous settings did still work. Later I upgraded to master again to collect more info. This time I ran much longer and started to do work again. After maybe 30 minutes the "left" screen suddenly became normal. The static content disppeared, the desktop icons appeared, the panel was now only on the "right" screen. To my surprise that (correct) state also appeared after a reboot.
Is it possible that you're actually finding an issue with xfdesktop? The root window - which seems what is not updating - is drawn by xfdesktop and if you have configured xfdesktop to display your icons on the primary monitor that happens with a certain delay. While xfdesktop listens to changes of RandR's primary setting it takes a bit to reload.
Created attachment 8409 x.tar.xz I created a fresh user, removed .cache, .local, .config, and reconfigured a few things. Then logout, login, the left non-secondary screen is not updated. I did not check if it will ever come back. Instead, the sddm mirror screen is shown. Logging in with my main user, the laptop screen is shown.
The config you attached is the one from the fresh user with the faulty profile? From the config itself it seems that the laptop display should be enabled. As I don't have those displays it's hard to reproduce this for me, but maybe you can also post your valid config from your other user so I can diff them. Finally, which state is your xfce4-settings in? (Git commit hash would help) Also, which version of xfdesktop are you running? Your problem sounds a bit as if it were unrelated to xfce4-settings, but it's hard to be sure...
dmesg output may also help...
This is git.xfce.org#master. I think xfconf.git#6f11cc65a2213f424728b5a0d25b1b63c19e773e "Bug #15122: xfconf: disable gsettings backend by default" fixes it for me. Since I use --disable-gsettings-backend, the secondary screen always comes up just fine.
Ok, thanks for the update! *** This bug has been marked as a duplicate of bug 15122 ***