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Disabling the “Initialize XR on Startup” option could cause this issue. Please open the Project Settings panel, navigate to the XR Plug-in Management page, and select the Universal Windows Platform tab. Ensure that “Initialize XR on Startup” is selected.
If you are new to MR development, please refer to the following links to check your settings.
Configure the project for the HoloLens 2 manually
Resolving incompatible settings
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