Hi,
Thank you for the details, it helps a lot!
The plugin is actually matching that product, but there were also relevant matches from other post types (posts, pages) that had a bit higher relevance in general, so those were displayed first. When I incresed the limit, the other product was there as well.
I guess you rather want an equal number of results from each post type, and for that, I have made the following change: https://i.imgur.com/3VzgH6O.png
