This KB addresses the following error when navigating to Guests -> Active Sessions:
Row query failed: ERROR: invalid regular expression: brackets  not balanced
This error can occur on on Amigpod version 3.5 and earlier. To resolve the issue, go to Customization -> Forms & Views. Select guest_sessions and choose the option “Edit Fields”. Find nas_name in the list of fields and select it; choose the option “Enable Field”. Return back to Guests -> Active Sessions and confirm that the page loads without an error.