Rank Math will read all the content which are wrapped in the tags. So for heading test to pass, the text should be wrapped in the heading tags: h2, h3, h4, etc. Even though on frontend I see the h2, h3 headings on backend it looks like you are using a shortcode or the theme uses a text and converts it to heading on the frontend. There is no way, Rank Math could read this content as a heading since they are not wrapped in the headings.
I hope that helps. If there is anything else, please let us know.
I am left really confused as you say my theme is now compatible but it isn’t reading title blocks for whatever reason.
Here is what my theme provider (who you have been communicating with) has to say-
Hi Wesley, I don’t know why RM is not reading these headings, maybe because they have specific classes, in any case i would not rely 100% on RM analysis tool and would use a front end tool to double check. Here is a great one: https://www.internetmarketingninjas.com/seo-tools/seo-compare/ include as many links you need and it will extract all the data for you.
For me, It doesn’t make sense to have RankMath and then have to rely on another tool to check basic things like headings and titles.