Custom backoffice search?

Hi,

I’m trying to add custom properties to the backoffice search, specifically for being able to search for tags on media files. I’ve followed the instructions at Backoffice Search | Umbraco CMS and it works when searching via the magnifier icon in the top-right of the screen, but not from the search bar inside the Media section. Do I need to add anything for it work there too?

Thanks in advance!