Per the Facebook Graph API, pages with fewer than 100 likes/followers do not have Insights generated for them. 

https://developers.facebook.com/docs/graph-api/reference/v2.12/insights


Insights are only generated for a Facebook Page that has more than 100 people that like it. 
Likewise, demographic metrics, such as age, gender and location, are available in Page Insights once there is data for 100 or more people.


If you are using a page with fewer than 100 like, you may get little to no data from this connector due to this limitation.