Mutli Tenant - Swtich not available

Hi There, 

this weekend i created a new tenant with my admin user. At the same moment the admin user was created as global admin in the new tenant as a member. Now I have the problem i can switch in aad the tenant but not in the admin portal. I'm global admin in both tenant, what I'm doing wrong?

at the moment I did a workarround with a new user as global admin...

Regards, 

Tobias