Hugo Module: Missing template when imported module imports a theme

My personal website (Mod 1) is using a Hugo Module as theme (Mod 2). Now I created a test Hugo Module (Mod 3) which only include content files.
It itself imports my personal website (Mod 1). The idea is to be able to create a content only repo, and still allow editors to preview the whole site on their local machine, even though they don’t have access the main module’s repo.

When running hugo or hugo serve from Mod 3, I have errors of missing template files

failed to extract shortcode: template for shortcode "notice" not found

I guess it’s the first error encountered, but general problem seems to be the layout files from the theme are missing.
When running hugo or hugo serve from Mod 1, everything works fine of course.

I tried with a repo which does not import a theme, and everything works fine, which makes me think this is not a problem of “recursive imports”.

I also tried importing the theme as a regular “imports” (rather than `theme:[...]), with same results.

Here’s the repos for