Multisite Mapping Domain Bug infinite loop redirection wp-login

Hi !
I don't understand.
I have read every posts about infinite loop redirection but I can't manage to solve this problem.

So, I have :
- wp multisite with many wpmu plugins installed.
- everything was ok until I install Mapping Domain.
- My domain names are all correctly set and linked with my subsites.

-> "myfirstdomain" is 'linked' with "myfirstdomain.ca" (and I am admin).
-> I can login with maindomain.com/myfirstsubdomain or http://myfirstdomain.ca
That's OK.
I am connected and I come on the frontend dashboard.

Now I'm trying to go in my admin dashboard I'm always redirected on http://myfirstdomain.ca/wp-login.php?redirect_to=http%3A%2F%2Fmaindomain.com%2Fmyfirstsubdomain%2Fwp-admin%2F&reauth=1

Impossible to go in the admin area...

I have tried with 3 browsers, same problem.
I have tried to clear cookies, the same...

in wp-config.php, I have tried with and without comments but the same :
define( 'SUNRISE', 'on' );
define('ADMIN_COOKIE_PATH', '/');
// define('COOKIE_DOMAIN', '');
define('COOKIEPATH', '');
define('SITECOOKIEPATH', '');

Maybe there and issue with wp-rocket cache (I have tried to empty it too) or with config in htaccess ???

Thank you in advance for your help !
And, of course, have a good day !