As a manager of a Google Shared Drive why can't I add folders?

I have the "manager" role on a google shared drive, yet I am unable to add files or folders to it.

All options are greyed out on the (right click) context menu. If I try to drag and drop - it gives the message, "you need to be a manager on {shared drive} to move to this folder".

I already have the manager role, and can confirm this by checking "manage members".

What could it be?