Domain Mapping forces mapped domains to ssl

Hello - since updating the Domain Mapping plugin to my mapped domain sites are being redirected to https on the login page.

So for instance this subdomain: is mapped to but when i try to log in it is being forced to and a warning that the wrong certificate is being used.

Previously when I ticked the box to force https on login pages it only did this for the original domain, not the mapped domain.

All mapped domains are showing as validated and all mapped domains are http, not https. I do have some unmapped domains, for instance and if I turn off 'force https on login page' then I get a strange looking login form. You can see the odd form here:

Prior to updating the site this all worked quite well.
Any help appreciated.