When a project is using MidlRT with modern idl turned off (ModernMidlRT property is false), then MidlRT calls WinMdIdl.exe to turn the winmds into .idl files. This command line chokes on these WindowsAppSdk references, because they aren't referenced as full paths, and msbuild doesn't seem to be looking at the HintPath property. This causes "file not found" build errors to pop-up.
The WindowsAppSdk nuget includes several references to winmds that look similar to this:
When a project is using MidlRT with modern idl turned off (
ModernMidlRT
property is false), then MidlRT calls WinMdIdl.exe to turn the winmds into .idl files. This command line chokes on these WindowsAppSdk references, because they aren't referenced as full paths, and msbuild doesn't seem to be looking at the HintPath property. This causes "file not found" build errors to pop-up.