The support staff is asking you to check /proc/parental-control/, but that only shows the current broken runtime state. It doesn't tell them why it's broken.
If you check your configuration directory: ls /etc/config/parental_control* you will likely see both parental_control and parental_control_v2 coexisting. The issue is that the developers failed to implement a migration path for the config files during the v4.9 upgrade.
They seem to be ignoring the root cause—that the old config wasn't migrated to the new schema—and are instead wasting time on remote debugging sessions. I've documented the scale of these upgrade failures in my own thread, where the damage went far beyond just one broken feature: https://forum.gl-inet.com/t/gl-mt6000-critical-issues-in-v4-9-upgrade-configuration-loss-and-security-regressions/69578.
Unless they address the fact that they didn't perform a proper v2 transition for these configuration files, they won't find the 'root cause' because they aren't looking at the right place