Keycloak session cluster

Hello, we are configuring keycloak for small environment. For better setup it was decided to make cluster system with mostly failover purpose. The cluster is configured succesfully and managed by wildfly without any problems. But we have some issues with the session clustering. Setup consists of two servers. Owners for each of session distributed cache was set to 2. But still if one node go down, the other one requires authentication. What can be the reason and what better to look for in logs?