Hi,
1. I assume you are trying to display attachments within an Elementor posts container? I’m afraid that is the problem then – Elementor simply does not allow that, it removes them and there is no way to get around it. This came up before, and there was no luck, we even tried contacting some of their developers, but we could not work out a solution.
2. I’m afraid no, the grouping only works in the plugin results container, when using the vertical results layout.
3. You have selected to use the index table engine, but on the index table settings only attachments are indexed and not the “post” and “page” custom post types. Whenever a search is triggered with a phrase, it will return nothing, as there is nothing in the index.
4. I just checked that search instance (id=2), but it is still set to 10 items: https://i.imgur.com/XAu6Tya.png
If you increase that number, it will surely increase the results count there.
