The only upside to all this is that I'm not alone.
BUT I HAVE A NEW FIX!
OK, "fix" is a bit strong, but this is easier than restarting Windows Explorer. Win-D to show desktop and then bring it back. I triggers their little "bounce up" animation the way minimize / restore or change desktops does and this gets the blank ones to refresh.
I can reliably trigger the loss by switching desktops around I just went 6/6 on restoring the lost ones by Win-D.