Conf Cloud REST API Create Group does not give group product access

When creating Groups using Confluence Cloud Rest API ( https://developer.atlassian.com/cloud/confluence/rest/api-group-group/#api-wiki-rest-api-group-post ), then manually adding users to the created group, then trying to get group members ( https://developer.atlassian.com/cloud/confluence/rest/api-group-group/#api-wiki-rest-api-group-groupid-membersbygroupid-get ), the users are not being returned (Getting 0 users, even after waiting incase it is a cache problem).

Also, when manually deleting a group in Confluence, the Confluence Cloud REST API still returned that group. ( https://developer.atlassian.com/cloud/confluence/rest/api-group-group/#api-wiki-rest-api-group-picker-get )

And now without any changes the same API requests work correctly as expected - so I would question if this was just a hiccup with the REST API’s, or if groups/users in confluence cloud are cached/not updated instantly when API calls are made to create new groups?