Hello,
Some users recently have been reporting trouble working with HoloLens 2. See this forum post for more - Does this plugin support HoloLens platform packaging? - #4 by agallegos
It sounds like you may be running into a slightly different issue though. To confirm, you are able to deploy and run the app? Is there anything at all on the screen?
Also, have you seen any error messages or logs that might show a problem?