Google finds the root site and not a specific website domain name

Hello,

I have a Multisite installation on lets say https://www.my.pages. I have a page https://www.my.pages/client1 and a domain mapping (WPMU plugin) https://www.client1.page, so it works. I have https://www.client1.page/sitemaps.xml with proper links etc. For some reason Google indexes https://www.my.pages/client1 instead of https://www.client1.page.

Can any one help me to figure out how I can fix this?

Best regards
Danila