The ordinary Chapter numbering for page numbers relies on the built-in heading styles. Those styles are special: Why use Microsoft Word’s built-in heading styles? by Shauna Kelly

1. You may be able to create styles that will work by basing them on the built-in heading styles. I have not tried this.
2. Numbering should be done using styles attached to numbering following the instructions given in How to create numbered headings or outline numbering in Ribbon Versions of Word by Shauna Kelly
3. You could also incorporate a StyleRef Field in your header/footer as a part of your page number. See Useful StyleRef tricks by Suzanne Barnhill, MVP.