Blazor "dotnet watch run" and "VS 2019 Preview" issues with .NET 5.0.1 update

I have a Blazor project which was working fine. Few hours ago updated VS 2019 to the latest “Version 16.9.0 Preview 2.0”. I also updated "Microsoft.AspNetCore.Components.WebAssembly" Version="5.0.1" Nuget package. I have done several Clean, Rebuild even restarted VS 2019. But still getting the same outcome.

1. Newly opened VS instance with Blazor project builds correctly no messages in the “Error List” window. dotnet watch run command works. Site opened in the browser.
2. Smallest code change (only added a space) will result nearly 100 build errors in the “Error List” window, meanwhile got “Build succeeded” status message. Also if I start the application from VS (press F5) it runs. But app works correctly in case of Server hosted mode. Blazor Web Assembly app looks very weird. It seems isolated CSS was not collected for the app.
3. Already running ‘watch’ detects code change and also rebuilds the code with the error below:

Error in dotnet watch run console: C:\Program Files\dotnet\sdk\5.0.200-preview.20601.7\Sdks\NuGet.Build.Tasks.Pack\build\NuGet.Build.Tasks.Pack.targets(221,5): error : The given key 'tfm_raw' was not present in the dictionary.

As I know .NET 5.0.1 update was released recently. But I think it should be a “final” package not a preview? Because checking installed apps on my computer VS was installed a Preview package.

[zkat]

@majorimi the patch has been merged into the appropriate preview branches for VS and .NET SDK, so this should be fixed with the next preview. 😃

[zkat]

No it’s definitely a bug, don’t get me wrong! I’m gonna work on getting this PR merged ASAP so we can get you unblocked 😃