I don't think http and https would have matter, https is like a standard nowadays, in order to check properly, please try the following:

  1. Check your image link and make sure it is working
  2. Visit this FB debugger page - https://developers.facebook.com/tools/debug/ and check if something else is wrong.

About

Geeks Mental is a community that publishes articles and tutorials about Web, Android, Data Science, new techniques and Linux security.