The BC + DC system property needed to set the URL to RH-SSO is missing:

-Dorg.uberfire.ext.security.management.keycloak.authServer=<RH_SSO_URL>

This property (amongst other changes to the WAR) is needed so BC can access RH-SSO and list groups and users from it. Without this, errors may happen during use of some features which depends on these informations.