If you want to change the color for the all buttons on your site, you need to use settings that are provided in the Default buttons and Accent buttonsareas.
The “All buttons” selector in Advanced button styles can be used for changing the typography only: https://take.ms/QU805 , this selector is not designed to change colors.
Please clarify which selectors you want to use from the Advanced button styles, so we can investigate it. Or clarify, which settings are not working on your side and send access to the admin dashboard so we can look closer at it.