If I may throw my hat into the arena....

Here's what commonly throws people when they are making documents in our office. They will create Section 1 (No page numbers). Then Section II and try to alter the page numbers, Section III with new page numbers, etc. Then they go back and see that Section II lost it's roman numerals and section one is acting up as well, etc.

The default settings for "Same as Previous" is a sneaky feature which - if not aware - could alter the work "behind you" as you progress forward in your document. Additionally, having your layout set to First Page Different could toss a few extra gremlins into the formatting process.

Here is my best advice. Start out clean. If you do not need FIRST PAGE DIFFERENT, turn it off for every section. Then remove every page number from your document ~~ for now. (I find it best to start with a clean slate if you are not 100% comfortable with Sections/Headers/Footers). Then disable SAME AS PREVIOUS for every header/footer in your document. This will help prevent accidents.

With these features in place, you should be able to go to Section 1 and add your page # (if necessary). Go to Section 2 and add your roman numeral page numbers. Section 3, insert page numbering.

If you do this and your document is still struggling, stop a moment and repeat the steps in a brand new (clean) template. If the new document behaves differently than the existing document; perhaps a container/template issue.

I hope this helps.