Just to close out this inquiry:
1. There is a scaling issue with large models (10x10km) when using Inspectors. The slop for the mouse click is not large enough to register the click on an object.
2. We found that the bug I was trying to track down using the inspector had to do with displaying agents with changing geometries in GeoMason. I added a line of code provided by Joonseok Kim, and it solved the display problem:
I hope that this saves time for others struggling with the same thing.