Hi Josh,
That does sound strange.
You mentioned the following reproduces the issue.
"If I set the breadcrumb to a group defined in PC (which has a rule set to include all devices that are members of a specific Spectrum Global Collection)..."
You mentioned that it also works well when set to a random GC.
"If I set the breadcrumb to Inventory > Data Source > Spectrum > All Spectrum Global Collections> random GC..."
If you reproduce using the same specific Spectrum GC the PC Group membership is based on does it work well?
Does the PC Group membership match the membership seen in Inventory > Data Source > Spectrum > All Spectrum Global Collections> GC_Groups_members_based_on?
Thanks,
Mike