[BUG] ERROR Automation017: Fail to get the root element of a process(11548)

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Describe the bug

I am trying to integrate Axe.Windows into Microsoft-ui-xaml testing pipeline and am running into some issues. It is returning this error:

Axe.Windows.Automation.AxeWindowsAutomationException: ERROR Automation017: Fail to get the root element of a process(11548): System.ArgumentNullException: Value cannot be null.
Parameter name: element
   at Axe.Windows.Actions.Contexts.ElementContext..ctor(A11yElement element)
   at Axe.Windows.Automation.TargetElementLocator.LocateRootElement(Int32 processId) ---> System.ArgumentNullException: Value cannot be null.

You can find the PR here, and the pipeline results here.

The VerifyAxeScanPasses pass locally with MSTests / TestExplorer via VS Studio but not with TAEF. It's failing trying to find the root UIA element of the MUXTestApp window, but I'm unsure why.

Desktop (please complete the following information):

• OS: 19h1, rs2-5
• Accessibility Insights for Windows Version: n/a
• Target Application: [e.g. Chrome, Wildlife Manager]
• Target Application Version: [e.g. 22]

Additional context

Priority requested -