Defender Mask URL and Mapped Domains.

I activated the mask URL feature, all good, but I'm regarding about that in multisite with subdomains mapped using the domain mapping plugin.
I cannot access the admin for these subsites because they redirect to the same URL that the wp-login.php redirects (set in the defender -> mask login Section).
Is there any option if the member tries to access the mysubsite.site.com/custom-login the member be able to log in, not only using the mapped domain?