Not too sure what's wrong with test here:

Failed Test_UniformGrid_AutoLayout_FixedElementZeroZeroSpecial [275 ms]
  Error Message:
   Test method PrimitivesExperiment.Tests.Test_UniformGrid_AutoLayout.Test_UniformGrid_AutoLayout_FixedElementZeroZeroSpecial threw exception: 
Microsoft.UI.Xaml.Markup.XamlParseException: XAML parsing failed.
  Stack Trace:
      at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|20_0(Int32 hr)
   at ABI.Microsoft.UI.Xaml.Markup.IXamlReaderStaticsMethods.Load(IObjectReference _obj, String xaml)
   at PrimitivesExperiment.Tests.Test_UniformGrid_AutoLayout.Test_UniformGrid_AutoLayout_FixedElementZeroZeroSpecial() in D:\a\Windows\Windows\components\Primitives\tests\Test_UniformGrid_AutoLayout.cs:line 77

Flipping it to use a backing test page with the new setup and trying locally.

We'll see if this works, had some weird issues running tests locally, but this one passed for WinUI 3, which it wasn't in CI. Though was getting other errors from XamlReader for UWP... I think there may be some threading issues when trying to run the old test methods in VS. I know for the extensions I had to spend some time updating the DispatcherQueue extensions to the new test syntax to better make use of the async support we have.

Just fighting .NET Native now it looks like!

Going to see if this runs better when being integrated (also so we don't have to wait for this to succeed twice). Had run tests and build UWP locally, so should be good here.

Wondering if we hit shared VM resource constraints at certain times/days of week and maybe that's why its an intermittent issue?