Hello,
Gluu CE is behind paywall now. You have to purchase subscription to continue with Gluu CE.
You can use [Janssen](https://docs.jans.io/v1.1.5/).
Regarding your Cache Refresh issue: most probably you are not using proper ObjectClasses for the LDAP server which you are pulling information from.
You can get more info in log if you make oxTrust logging to DEBUG / TRACE.