Projects in same-named solution folders are omitted

[doxxx]

- [ ] Include the log file upgrade-assistant.clef that is produced in the working directory
I cannot because the issue occurs before running the upgrade.

Describe the bug

When performing a upgrade to central package management, the Select Components To Upgrade view shows an invalid solution structure when there are multiple subfolders that have the same name, e.g. A/B/XXX and C/D/XXX. The contents of the one occurrence of that subfolder is used in all other occurrences. This is not simply a UI glitch, it actually affects the upgrade because the projects which are not shown are not upgraded.

Here's a real example. First the Solution Explorer view showing the correct folder/project structure:

Notice the three subfolders named Model which each contain different projects.

Now here's the solution view in Upgrade Assistant:

Notice that all three subfolders named Model have the same two projects.

To Reproduce

See above.

Further technical details

• Windows 10 64-bit
• dotnet SDKs:
  5.0.408 [C:\Program Files\dotnet\sdk]
  6.0.302 [C:\Program Files\dotnet\sdk]
  7.0.100 [C:\Program Files\dotnet\sdk]
  9.0.100 [C:\Program Files\dotnet\sdk]
• Upgrade Assistant Visual Studio Extension v0.5.829.41291