This could be a very simple answer so I apologies in advance, Seems like Jamf is unable to retrieve hardware information on some machines, they have all been enrolled via user-initiated- no invitation method. Was wondering why this is happening and any potential solutions. 
Question
Hardware information not being populated.
+1
+12@jannaid We see cases like that when users start to enroll their Macs, but then decide not to install the MDM profile, eg because they think this would give us too much power on their Macs.
+5I second what @jannaid has said. I have seen this were the user does not install the MDM Profile or you use Jamf QuickAdd and that fails for whatever reason leaving the device in Jamf but with no actual information filled in.
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.