Hello TMacD and welcome,
I've seen a few (too many) models like this with lots of filters and lots of summaries - they get really hard to manage. It sounds to me that you could do this with two summaries, using the sales agent field as the first key field, and export the summary to burst to new files on each instance of a new value of the key field. I'd suggest also duplicating the model and running one summary export only from each project to help narrow down the possible source of the problem.
Once you've created 63 exports (are they Excel files? do you have each summary on a separate worksheet, so each agent gets one file with two tabs?) how do you distribute them to the users?
Hope this helps,