I suspected as much. I have a number of post types that should be displayed differently, so I added an ACF text field to each called xx_type. Then I’m using a snippet to automatically fill in that field with the post type e.g. “Dogs” or “Cats” triggered by acf/save_post.
In the Search Results template, I have a posts module with a Custom Post Layout that looks like this:
[wpbb-if post:custom_field key='xx_type' exp='equals' value='Dogs']
[wpbb-if post:custom_field key='xx_type' exp='equals' value='Cats']
It works if that helps anyone else, but I’d be happy to hear any better ideas.