VS2017 15.3 (and other?): Auto add Reference is not using a ProjectReference

In  VS2017 15.3, and maybe other versions, with lightweight solution loading enabled.

When we use the Alt-Enter shortcut to add a missing reference to a project contained in a solution, it creates sometimes a ProjectReference, and sometimes a Reference, I cannot identify exactly why sometimes one is used over the other.

The problem is that when it's not adding a ProjectReference, it breaks the build order as the project dependency is not detected properly.