Campaigns created in Drupal do not contain selected site content when sent

Email received from campaign created in Drupal does not contain any site content if selected at the time creation.
It includes only content added in "Content" area and not the site content added from "Insert Site Content" area. Ideally it should include both. Node's are not getting inserted into mail.

Steps to reproduce -
1) Install mailchimp version - 8.x-1.2
2) Enable mailchimp , add API key
3) Add a new campaign in Drupal - (admin/config/services/mailchimp/campaigns/add)
4) Fill out all the mandatory fields
5) Do not select Template in "Template" field. By doing this, "Content Sections" would be editable.
6) Add some content in "Content Field"
7) Under 'Insert site content', select entity type as 'Content' and then select any node from your site and a view mode for that node.
8) Send that campaign.
9) Check mail received by the respective subscribers for that campaign.
10) Mail will contain only the text entered under "Content" field and not the node inserted under 'Insert site content'

Node information should get included in the e-mail sent.