SharePoint Online - Move To missing Tennant missing other sites missing other libraries.

Hi team,

I have an HR document library, with about 750 document sets in it.

Using modern view of the library if I tick the circle to the left of the document set, then click Move To the popup panel on the right appears .....

BUT

Under choose destination I don't get current library or Your onedrive (as I do in other site's libraries).

Nor do I get a choice of other sites in the Tennant. 

It only shows a list of all the document sets in the same library.

Any suggestions on how I can help the HR team out with how to move documentsets out of this library and into the "Exited staff" library ?

I've tried: multiple logins (same experience for member, owner, tennant admin), removing all my own favourited sites (there were a lot, same experience), all other libraries in the HR site have the same problem except "Site assets" library (not sure why).