When I have a run-in heading in my EDUPUB publication like so:

<section aria-labelledby="sec-heading">
    <p><span aria-level="1" role="heading" id="sec-heading">Section heading (run-in)</span> Section contents.</p>
</section>

when validating with epubcheck 5.0.0 under the EDUPUB profile, I get the following error:

epubcheck error: ERROR(RSC-005): […]: Error while parsing file: section does not have a heading.

https://idpf.org/epub/profiles/edu/spec/#h.frvc45xf6cia 3rd paragraph suggests that I should be able to use aria-labelledby to associate the section with its heading, which cannot be a ranked HTML5 heading at that place due to p's content model restriction. That is why I use role="heading" and aria-level="1" as the equivalent to h1.

Is this an epubcheck issue, EDUPUB issue, or me misunderstanding the relevant spec's wording?