The Administration UI is hard coded to 5000 so as to prevent excessive memory consumption in CAPC.
However, the full member list can be see under Universal Lists like Inventory lists. The limit for these can be increased by doing the following:
2. Find the variable UniversalList.Limit and increase its value as desired. This will allow more than 5000 items to be viewed in the Inventory lists.
Note: this will use more memory in PC as it stores more rows. The Inventory can be used to confirm full membership of the group of interfaces/etc.