The queue_log file (usually found in "/var/log/asterisk/queue_log") contains all the queue information that QueueMetrics uses to create the reports and Live stats.

If you PBX is not writing data in the queue_log file, make sure that your Asterisk is configured to write the information on the file.

It should be enough to add:
queue_log_to_file = yes

To the "/etc/asterisk/logger_general_custom.conf" file, that you find on your Asterisk machine.

Restart Asterisk and make sure that the data is being written.