Your user now has access to necessary indices for data in Elasticsearch but no access to Kibana, give them kibana_admin role in the role mapping or look into kibana authorization for more finegrained access to kibana.
If this doesn't solve your issue somehow, enable DEBUG logging for logger.org.elasticsearch.xpack.security.authc.support.mapper and read through these logs, these will have all the necessary information. If I understood correctly, you already have a support contract so it might be worth it to raise this through your support engineer to get more timely answers and more detailed assistance.