Verified on the Sat 6.5.2 Snap.
$ insights-client --register
You successfully registered 88aa0d7c-eb30-4620-ba0f-1857a6cb8559 to account 5779551.
Successfully registered host rhel7-client.example.com
Automatic scheduling for Insights has been enabled.
Starting to collect Insights data for rhel7-client.example.com
Uploading Insights data.
Successfully uploaded report from rhel7-client.example.com to account 5779551.
$ insights-client --status
System is registered locally via .registered file. Registered at 2019-07-24T13:49:46.177407
Insights API confirms registration.
$ insights-client --display-name="WhatWasTheBugAgain?"
System display name changed from None to WhatWasTheBugAgain?
The new name is correctly displayed on the Insights Inventory page.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.