Great to see your leveraging the Big Data Insight Reporting for UC for your Avaya deployment. Note that the new release of Reporting Solution 11.4 has several enhancements including more efficient SQL disk space usage and more flexible partial back options.
This particular out of box report you mention, Avaya Trunk Busy Hour Number Channels Occupied, shows all a line chart and bar charts of the utilization of trunk groups for the selected PBX’s and Trunk Groups and within the chosen time period. It plots the Busy hour max channels occupied, busy hour average channels occupied, the busy hour and the max active channel capacity.
That does sound like a problem you describe so please make sure to open a case with IR Support so that we can work more closely with you on it.