Reviewing through your description, the message outlined "Skipped: user has not yet earned any rewards and does not exist in rewards system, visit their profile in Jive to add them to rewards" is expected if the account has not yet accessed your instance or performed an action that would award them points as users are created in the Rewards system the first time an action is triggered for their account.
I can't find documentation on how to actually do this.
This action refers to viewing the user's profile within your Jive instance, for example searching for the user and selecting their username should take you to their profile:
Further, some users are showing in the rewards system and it's still giving this error.
For this behavior I would recommend submitting a case in your customer group ( MyJive Secret Support Group Administration FAQ ) as a next step so that a member of our support team can review through your specific instance for additional information. When submitting the case, if you could include a couple of usernames for accounts where you see this behavior, it should assist with their investigation.
Thanks Jesse, will do.