I am currently start using Visual Studio 2017 along with Team Foundation Service that is why this question arise.
When I am working with Visual Studio 2013 and add new item to Solution and then do Pending changes from Team Explorer, It does not included newly added item to solution or project.
I have sample problem with same scenario in VS 2017.
Actually I want to work with TFS and Visual Studio 2017/2015/2013 but not want to bind solution. Only Team Explorer level binding I want to use.
If you create a new item and then check both in VS2013 and VS2015, please make sure you are using the same workspace for VS2013 and VS2017.
If you create new items separately in VS2013 and VS2015, please make sure you add items by the same way and options. For TFVC, there are many ways to add files to source control: