Facebook Android SDK AppEvents not recognizing users on Insights Dashboard

How are you?

We are integrating our App with AppEvents. To do so we are following this guide.

We are first trying to register simple default events after user logs in and interact with the App (ie AppEventsConstants.EVENT_NAME_ADDED_TO_CART). As far as we could see, data is being posted ok (App Id and logged in user Access Token seems to be ok) and we get no errors on the app.

When we enter to Events section on Insights the data we sent is there but the info about the user isn't being processeed. For example, only gender and country filters with "Unknown" return results.

We are using SDK v3.23.1.

Thanks in advance!