How to debug with Embedding C# sources in PDB?

This is my csproj file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>
  <PropertyGroup>
    <!-- Optional: Embed source files that are not tracked by the source control manager in the PDB -->
    <EmbedAllSources>true</EmbedAllSources>
    <!--<EmbedUntrackedSources>true</EmbedUntrackedSources>-->
    <!-- Optional: Build symbol package (.snupkg) to distribute the PDB containing Source Link -->
    <IncludeSymbols>true</IncludeSymbols>
    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
    <AssemblyVersion>1.0.2.0</AssemblyVersion>
    <FileVersion>1.0.2.0</FileVersion>
    <Version>1.0.2</Version>
  </PropertyGroup>

</Project>

When debugging, the PDB file can be downloaded correctly, but the source file cannot be found through the PDB. The debugger still pops up the dialog box of selecting the source file.