Hello,
Could you make a backup of your current configuration, reset your device to factory default settings and check, if you are able to view the mobile usage pages?
Otherwise, I would like you to attach a troubleshoot file to your question. Please, make sure the issue is present, then access router's WebUI, go to System -> Administration -> Troubleshoot section and download troubleshoot file from there. The logs in the file might provide more insight into the issue.
Best regards,