Can't login to the admin area on multisite sites with Domain Mapping plugin

I have a subfolder multisite setup (WordPress 4.1) with the Domain Mapping plugin installed (4.2.0.6) and the following options set:

– Admin Mapping – Original Domain

– Login Mapping – Mapped Domain

When I visit the login page for the core site (coresite.com/wp-admin/, for example) I get redirected to coresite.com/subsitefolder/wp-login.php. I enter the super admin’s username and password, get logged in and then taken to the dashboard for that site. Fine, all works.

However, when I visit the login page for one of our sub sites (subsite.com/wp-admin/, for example) I get redirected to subsite.com/wp-login.php. I enter the super admin’s username and password but this time I get “ERROR: Incorrect username or password.”.

I can’t seem to allow the user to login using the mapped domain no matter what I do. I have set both options back to “Original Domain” for now and that works fine.

It’s just really annoying because I can’t use preview for posts/pages, and the admin bar doesn’t appear on the front-end because WordPress doesn’t see the user as logged in because of the different domain.

Any help would be much appreciated.

Thanks,

Jams