Inter-Project dependencies resulting in Metadata file not found

Question

I have a series of C# projects targeting .NET 9 in one Visual Studio 2022 Community solution. These are mostly meant to stand alone, but do rely on each other for somethings. Now an issue has cropped up that I don't understand.

SeverityCodeDescriptionProjectFileLineSuppression StateDetailsError (active)CS0006Metadata file 'B:\Contents\Will Pittenger\Goodies\WillPittenger.Goodies.Sounds\obj\NoWindowsDebug\net9.0\ref\WillPittenger.Goodies.Sounds.dll' could not be foundWillPittenger.Goodies.PowerShell.SoundsB:\Contents\Will Pittenger\Goodies\PowerShell\WillPittenger.Goodies.PowerShell.Sounds\CSC1Error (active)CS0006Metadata file 'B:\Contents\Will Pittenger\Goodies\WillPittenger.Goodies.Tools\obj\NoWindowsDebug\net9.0\ref\WillPittenger.Goodies.Tools.dll' could not be foundWillPittenger.Goodies.SoundsB:\Contents\Will Pittenger\Goodies\WillPittenger.Goodies.Sounds\CSC1Error (active)CS0006Metadata file 'B:\Contents\Will Pittenger\Goodies\WillPittenger.Goodies.Tools\obj\NoWindowsDebug\net9.0\ref\WillPittenger.Goodies.Tools.dll' could not be foundWillPittenger.Goodies.PowerShell.SoundsB:\Contents\Will Pittenger\Goodies\PowerShell\WillPittenger.Goodies.PowerShell.Sounds\CSC1Why am I getting these errors? The project is WillPittenger.Goodies. The problem is demonstrated by the Chasing-many-issues branch.I've tried restarting Visual Studio and rebuilt the solution many times. I've deleted cache files from the .vs folder. I also tried manually deleting bin and obj folders. Nothing helped.