[keycloak-user] KeyCloak access tokens not being cached

I have set up a keycloak cluster and generate tokens via /auth/realms/master/protocol/openid-connect/token. The problem is that an access token can only be used to perform subsequent requests on the SAME SERVER that issued the token. Attempts to make a request (e.g., /auth/admin/realms/master) on another server in the cluster results in a response of "Bearer" and an error in that server's log. Shouldn't the access tokens be available across the cluster? As a side node, the refresh tokens DO appear to be cached, so caching does appear to be working on some level. As a second question: What data is stored in the session and authentication caches? How does this relate to the access and refresh tokens?