can't login on subsite. Multi-domain AND Domain Mapping together

Hi!

I have an issue with both plugins and I confirm I use the latest version of both, of sunrise, and of WordPress

I tested this on a live site, and on a test site, with several different versions of sunrise.php, tested with and without single signon, cleared cookies, changes browser, etc...

I cannot connect to the dashboard with a subsite attached to a secondary domain, but only when domain mapping plugin is active, and the said login is NOT on a mapped domain

->> can login :
mainsite1.com/wp-admin
subsite.mainsite1.com/wp-admin
subsitemapped.com/wp-admin (mapped on a subsite.mainsite1.com OR subsite.mainsite2.com <- must check)

->> cannot login:
subsite.mainsite2.com/wp-admin (where mainsite2 is a additional domain entered into multi-domain, and pointing to the same install folder in my hosting panel)

I don't know if the issue was there before the new versions of those plugins, because I never had until now a customer on a secondary domain, without mapped domain, I need that now that a new customer want to keep her old site on her current hosting with her domain name, until her site is ready.

I talked the other day in the chat with one of your support staff, but after test, I told him it was working on a second test site, but it was my mistake, it was working on
subsite.mainsite1.com/wp-admin
but not on
subsite.mainsite2.com/wp-admin

on my live site, I have Pro Site, but on my other test, there is no Pro Site, and only a few other plugins.
the live site is on a dedicated IP, the other one on shared IP.

thank you very much in advance for your help
Have a great day
Patricia