When using Chromebooks on a network with SSL Inspector configured to "Inspect All Traffic" or "Inspect Google Traffic", you will need Ignore Rules to allow the Chromebooks to authenticate.
As of (August 4th, 2020) you will need rules for the following hosts:
|alt*.gstatic.com||m.google.com (see below)|
URLs in italics are new as of August 2020. They have been reported by other NGFW users but not obtained directly from Google.
m.google.com is just the mobile-friendly version of www.google.com. This entry may be optional; using it is likely to render your NGFW unable to inspect Google search traffic (for purposes of enforcing SafeSearch, &c.).
PLEASE NOTE: Google is known to change these addresses without warning.
To add the rules go to SSL Inspector Settings -> Rules -> Add Rule
The rule conditions should be "SSL: SNI Hostname" is: "<host>" and the Action should be "Ignore"