xfce can't change background image

Booted up today, running up-to-date Sparky GameOver, and XFCE will not allow change background image - right click -> set as wallpaper, and going into Settings -> Display its all placebo can click infinite times will not change, running xfdesktop --next will cycle to whatever was last 'set' (but again NOTHING IS CHANGING), and then crash the desktop, and it will not persist a log-in/log-out. Everything worked at last poweroff so this really is 'it just magically failed.' Tried moving a few test jpgs to /home, chmod 777 on test files, no difference it won't work. I have no idea how to get into any logs or terminal output of this to even begin to guess what is causing this problem, hence asking for help. All the GUI stuff acts like its working but it is not working. Have tried stupid easy stuff like rebooting, restarting light-dm and xfce, no changes.

Any ideas how to get a finger-hold into why its failing 'for some reason' more concretely?

EDIT
Some more playing around this is a bigger issue - all settings in 'Settings -> Desktop' are fake/placebo and nothing applies, there is no context right click on desktop working, no drag selection, etc. Everything else seems to be working okay. No idea how to get into this - any help greatly appreciated!

EDIT 2
Tried following along here: https://forum.xfce.org/viewtopic.php?id=16373

running xfdesktop --menu -> segfault

from dmesg:
Code: [ 604.938822] xfdesktop[7069]: segfault at 38 ip 000056320b36659a sp 00007fff3cd20ba0 error 4 in xfdesktop[56320b355000+38000] likely on CPU 15 (core 5, socket 0)