Server default Realm configuration in standalone.xml and host.xml differs  in host->profiles->http section.

In host.xml there is <mechanism-realm realm-name="Management Realm"/> while in standalone there is <mechanism-realm realm-name="ManagementRealm"/> (there is no space in "ManagementRealm"). It seems like a typo, because in domain mgmt-users.properties file mentioned "ManagementRealm" without space.