Just to confirm, have you already tried adding custom thumbnails using the steps mentioned in the Help Center article: https://goo.gl/75FYYJ ? Keep us posted.
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Just to confirm, have you already tried adding custom thumbnails using the steps mentioned in the Help Center article: https://goo.gl/75FYYJ ? Keep us posted.