Export realm and user data

Hi, We are currently on KeyCloak v8.02 installed as a windows service using Oracle provider and we are going to upgrade to KeyCloak v16 using PostgreSQL. Currently I am trying to export the realm and users data by using the below command.

sh standalone.sh -Dkeycloak.migration.action=export -Dkeycloak.migration.provider=singleFile -Dkeycloak.migration.file=keycloak-export.json -Djboss.http.port=8888 -Djboss.https.port=9999 -Djboss.management.http.port=7777

We have three realms and the data that is being exported just have the master realm data (not even the master users data). Can someone please help me figure out whats happening and how we can export and import the data while migrating to another version