Existing user on multisite not added to subsite

I’m using EDD 2.7.2 and EDD Auto Register 1.3.8 on a multisite installation.

If a new user makes a purchase, they are automatically registered as a user on the subsite unless they are registered elsewhere on the network. Although I wouldn’t expect the user to be registered twice I would have thought they would be added to the subsite – otherwise they can’t log in and upgrade, or obtain download links or license keys.

Is this the expected behaviour?

Thanks

Gareth