A SharePoint 2013 tasks list created through code was not connecting to the Out-of-the-Box (OTB) Project Summary webpart.
We created a task list through code using the REST api. This is fairly simple to do with the gd-sprest library, refer to this page for additional details. Regardless of the library you use to create a list, you must set the list creation information. The minimum information you need to provide is the title of the list and the list template type. Refer to this page for a list of the template types.
The Tasks list template is his explanation 107
When clicking on the link to “Create a Task List”, provided by the project summary webpart, I noticed the template type was set to http://theplumeapp.com/?page_id=18 171. This template was unknown to me, since I’m used to only dealing with 10x list template types. When looking this up, the template being referenced is TasksWithTimelineAndHierarchy. I updated the solution to create a list using 171, and the project summary webpart was now connecting to it.
When creating a tasks list via code for SharePoint 2013, make sure to use template 171 if you want the list to work with the “Project Summary” webpart.