Root users would often have full privileges to do what is required here, although it is possible something has been locked down. However unless you have some additional information you haven't noted here, I would not start by assuming this is related to privileges.
A helpful starting point to investigate further will likely to look in the tracker.log file that was generated while the inventory was being gathered. The logging in this file may give an indication of what happened during the inventory gathering process to point you in the right direction.
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