After upgrading to 7.0.18 from 6.4.22, exporting a template that has linked templates (directly or transitively) fails only for users with granular, group-scoped permissions. The same export succeeds for templates without links, accounts with global permissions or accounts without Host subgroups. This breaks routine team-scoped backups and CI/CD flows for templates.{}

Steps to reproduce:

1. Create (or use) a User group with access restricted to specific Template groups and Host groups, including subgroups.
2. As a user in that User group, attempt to export:

• • a template that links to another template, or

• • a template that is linked by another template (transitively)

Result:

Observe the failure:

• Web UI: HTTP 500 error page.

• API: Exception: Zabbix API error: {'code': -32603, 'message': 'Internal error.', 'data': 'CConfigurationExportBuilder::formatGroups(): Argument #1 ($groups) must be of type array, null given, called in /usr/share/zabbix/include/classes/export/CConfigurationExportBuilder.php on line 341'}

See attached log file from Zabbix frontend

Expected:
Successful export of the template to a file