OpenInWindowEx launches an external window

[Matt21886371mlg6]

While running the SDK examples on Windows 11, in attempting to run the ActiveViewVB sample from the Acrobat SDK, when opening a PDF file, instead of the file opening in the PDFView form, an external Acrobat window is loaded and the PDF is shown in Acrobat window (completely outside of the ActiveViewVB application).  Is there updated guidance on how to use the OpenInWindowEx functionality with Acrobat DC in Windows 11 that is not reflected in the SDK examples?

[Matt21886371mlg6]

This behavior only occurs when Protected Mode is enabled in Acrobat.  Adobe recommends turning Protected Mode on but I have found no guidance on how to make interapplication communication (IAC) work while still having Protected Mode turned on.  Why is there guidance for developing plugins while using Protected Mode (through the sandbox broker) but no guidance on dealing with IAC?