Newsletter emails: Query Loop for custom post type is reset to posts in email content

On WordCamp.org, we have custom post types for speakers, sessions, etc. They can be used in regular post content with the Query Loop block (for example, announcing speakers). When this is emailed out, the query loop does not show speaker names, but instead shows the latest posts on the site.

This post, for example, shows 6 speakers in the "group" taxonomy: https://us.wordcamp.org/2024/announcing-showcase-day-speakers-round-1/

But the email shows a list of latest posts.

It appears to be stripping both the custom post type and the taxonomy filter when rendering the email.

Start by tracing how newsletter emails render the Query Loop block, using the linked WordCamp example to compare regular post content with email output. Investigate preservation of the custom post type and the "group" taxonomy filter; done means the email lists the selected speakers rather than the site's latest posts.

Written by the indexing model from the issue text.