Look for components.tar.gz on support.
Follow the instructions in the README file to reproduce. It happens systematically with a clean config.
Additional info found after uploading the README:
1) In the README, notes point a) says "anonymous workspace", it should say "anonymous namespace"
2) If you do "find references" on "components" in the project containing the mk file, it finds references in the .mk file even though Tools->Options->Editing->Context Tagging->Allow mixed language references is set to "off".
3) If you open the nomk.vpw workspace and do find references on "components", a mysterious dialog appears that says: "No more references, pop from stack?" appears. Can you explain what this means? No matter what I choose (yes or no), the references window will show 2 unexpandable files.