Visual Studio & Circular Dependency Issues

I have a legacy system made up of 15 different projects, and when I tried to link to it from another Visual Studio, it complains that it cannot do it as it will cause a circular dependency.

My problem is that I can't see how this will cause a circular dependency, since the project I'm trying to link to ("XScript") doesn't have any validation to the project that is trying to link to it ('WPF_Forms').

From researching around here, I've found that people suffer from similar judgments, although their problems seem to have obvious circular dependencies.

I downloaded a demo copy of NDepend as recommended a few posts from here, and even though I've worked with various dependency tools there is no obvious link there.

I right clicked on the projects and used the Project Dependencies option, but I don't see any link. I also restarted Visual Studio and tried "Clean Solution" and "Re-build Solution" to no avail.

The only way I could think of is to refer to "XScript" by referencing an inline DLL and not the project itself, however this is a bit messy and I want to know why this is happening quite simply hack it.

Can anyone suggest anything that I may have missed, or any strategies I could use to figure out what is going wrong?

EDIT 1: The XScript used to reference WPF_Forms, but that reference has been removed (and the project is cleaned up and rebuilt with no dependencies showing in the Project Dependencies window. I suppose it's possible that VS saved the reference somewhere or what it thinks is that the projects are related in some way.

EDIT 2: Following BitBonk's suggestion, I used the used VS Code Map feature and worked out the topology of the project. XScript and WPF_Forms only refer to the main .exe file and nothing else. I am starting to suspect this is a VS issue and I may have to create a new project and add all sub-projects again to get it working.