Hi,
Sorry but i don't understand this:
To be functional a checkbox needs to always have a selected value, and so basically that can really be "fixed"
I have attached 2 screenshots from two different websites, in the first screenshot is a checkbox custom field that has no default values and works correctly and in the second is the checkbox custom field that has 7 default values (i didn't set these defalut values) and after i remove those default values from it and hit save, every time the default values reset.
Thank you