Thanks for your patience while I worked on a solution for your application. I am happy to report that I found a way to add a “Not Featured” custom view to the Media/Library grid view and the Media Manager Modal (popup) Window “Set Featured Image” Images dropdown list.
I have uploaded a new MLA Development Version dated 20230317 that contains the enhancement. You can find step-by-step instructions for using the Development Version in this earlier topic:
PHP Warning on media upload with Polylang
Once the Development Version is installed you must install and activate the example plugin. Navigate to the Settings/Media library Assistant Documentation tab and click the “Example Plugins” button. Type “featured” in the text box and click “Search Plugins” to filter the table.
You are looking for the “MLA Not Featured View Example” plugin. Find that plugin and hover over the title in the left-most column. Click the “Install” (or “Update”) rollover action, then go to the WordPress Plugins/Installed Plugins submenu and activate the example plugin as you would any other plugin. Make sure you have the latest version, 1.02, installed.
Once the Development Version and updated example plugin are installed and active you can test the addition of the “Not Featured” custom view. It is available on the Media/Assistant screen, the Media/Library grid view and the MMMW popup windows such as “Add Featured Image”.
This MLA enhancement and example plugin will be part of my next MLA version, but in the interim it would be great if you could install the Development Version and the example plugin and let me know if it works for you. Thanks for inspiring this long-wanted MLA improvement.