nikeo,
That's one of the things I tried to see if it did anything. The default (Twenty Fourteen) theme was activated and let it sit for a bit, then I reactivated the Customizr Child theme. I'm going to see if things change. I'll try to keep things updated on here as to what I try and find.
I also deactivated most (see above) plugins, then after a while reactivated them.
So far no 404 errors related to the location of parts of the theme.