I'm currently managing an O365 site collection with 100+ subsites, up to 3 levels deep. While cleaning up the environment, we've deleted all Site Assets libraries, simply because we weren't planning on using them.
Since then, I've noticed these Site Assets libraries re-appearing here and there, on seemingly random sites in the structure.
Is an action on our behalf triggering re-creation of these libraries? Are these re-created automatically by a timer job?
Activation of SharePoint Server Publishing Infrastructure or Wiki Page Home Page triggers creation of Site Assets Library. Can you please confirm if this is the case?
As far as I know, if you have a web site without the Site Assets library, and open the site in SharePoint Designer, you see a folder called Site Assets there in the Site Objects navigation panel. If you click on that, the Site Assets will be created by SPD automatically, without prompting you if you really wish to create it. The same is true for Site Pages.
As already mentioned, Wiki Page Home Page feature will create this library.
Additionally, SharePoint will create this library automatically when entering site settings pages such as Title, description and logo if the Site Assets library is not present. The setting page will result in an error the first time you try entering this site setting page, but SharePoint will automatically create this library behind the scenes.
