When you reduce the opacity of a text object that contains a list - either just a list or a list plus "normal" text, that opacity gets deleted once you have saved the file. It's not even saved into the PDF part of the file.
If you apply the opacity at the Character level or if you create an additional fill for the text object and then apply reduced opacity, it works.

Version 28.3
MacOS Monterey 12.7.1

Please see also: https://community.adobe.com/t5/illustrator-discussions/bulleted-and-numbered-text-opacity-bug/m-p/14512837#M402363