Generate metadata: Workspace failed with [Failure] Msbuild failed when processing the xaml file

**Operating System**: Microsoft Windows [Version 10.0.18363.1916]

**DocFX Version Used**: 2.58.9.0

**Template used**: default

**Steps to Reproduce**:

Use Microsoft Visual Studio Professional 2019 [Version 16.11.8]

1. Create a blank solution.
2. Add class library 'ClassLibrary1' for netstandard2.0
2.1 Modify triple-slash comments for the class1 to a meaningful comment.
3. Add custom control library 'WpfCustomControlLibrary1' for netcoreapp3.1
3.1 Modify triple-slash comments for the CustomControl1 to a meaningful comment.
3.2 Add project reference to class library 'ClassLibrary1'
3.3 Add namespace and datatemplate to 'Generic.xaml'.

```xaml
xmlns:lib="clr-namespace:ClassLibrary1;assembly=ClassLibrary1"

```
4. Build the solution. It should build without errors and warnings (see output window).
5. Add '"docfx.console" Version="2.58.9" to custom control library 'WpfCustomControlLibrary1'.
6. Build the solution. It should build without errors **but** 3 warnings (see output window).

**Expected Behavior**: The build should be completed without warnings.

**Actual Behavior**: The build completes with 3 warnings. The type reference of 'Class1' in 'WpfCustomControlLibrary1' is not found.

**Remark**: When I generate the metadata with the console command "docfx metadata -f" I get the same behavior.