Why do I now get a "Method Not Found" in Windows.UI.Xaml error when running my project?

Question

After doing a side-by-side installation of Visual Studio 2022 RC, I now get the following error in a project that ran fine before the install.The namespaces in the XAML page and codebehind seem to match. I have made sure that the targeted Windows SDK is installed. Any suggestions as to what else I should check? This is a UWP project. Thanks.

 Windows.UI.Xaml.UnhandledExceptionEventArgs}
        Exception: {"Method not found: 'Boolean System.Threading.CancellationTokenRegistration.TryDeregister()'."}
        Handled: false
        Message: "System.MissingMethodException: Method not found: 'Boolean System.Threading.CancellationTokenRegistration.TryDeregister()'.\r\n   at System.Threading.Tasks.AsyncInfoToTaskBridge`2.Complete(IAsyncInfo asyncInfo, Func`2 getResultsFunction, AsyncStatus asyncStatus)\r\n   at System.Threading.Tasks.AsyncInfoToTaskBridge`2.CompleteFromAsyncOperation(IAsyncOperation`1 asyncInfo, AsyncStatus asyncStatus)"
        Native View: 0x170119f0 <Information not available, no symbols loaded for Windows.UI.Xaml.dll>

Also, now when I try to create a new project using Windows Template Studio, I get an "Object reference not set to an instance of an object error with the following details:

 System.NullReferenceException: Object reference not set to an instance of an object.
       at Microsoft.Templates.Core.Gen.GenController.ValidateUserSelection(UserSelection userSelection, Boolean isNewProject)
       at Microsoft.Templates.Core.Gen.NewProjectGenController.<UnsafeGenerateProjectAsync>d__4.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.Templates.UI.Services.GenerationService.<GenerateProjectAsync>d__5.MoveNext()

I'm thinking these issues must be related.