But in my many-to-many relationship forms, it says "No (cpt) can be associated to (post title)". This is confusing to the user. I would rather it say "no results found" like the other forms, or "does not match available selections" or something like that.
Solution:
You can customize that message with WP filter "gettext", for example:
Since WordPress 5.9, if using non-Toolset blocks (including core blocks) with dynamic sources in templates, Views, or custom archives, errors are thrown and it may not be possible to edit the page.
