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Horizon View endpoints will not be displayed under Inventory Tab, This is a known issue and we are working with engineering to have the Objects displyaed for Horizon View.
As of now to check the Horizon View status, you would need to filter utilizing "End User Compute" under Findings and Recommendations, Which would give you the rundown of findings which are reported for Horizon.
If you would like to know the status of the endpoint, you can check the same from the Admin page of the collector.
Marking this question as correct answer due to inactivity. Please respond to this thread if the issue persists.