Populating reviews in-app is only possible if the correct listing is present in Reputation Management. If you have reviews showing on your live listing but not in the Reputation dashboard, it's very likely the wrong listing was pulled into Reputation Management or no listing has been found.
How to fix this:
Launch Reputation Management, navigate to the Listings tab > Primary Listings.
Remove the wrong listing URL if one is present, and then submit the correct URL for your listing.
Once the correct page is found, the reviews will start populating.