When checking the endpoint we use for collection of bulk stats /dataservice/data/device/statistics/approutestatsstatistics?count=10000&startDate=2020-07-13T10:30:00&endDate=2020-07-13T11:30:00 there is no data there to collect.
Cisco VManage is not populating the endpoint with data so there is no data to collect.
Release : 3.7
Component : Virtual Network Assurance For CA Performance Management
Issue was reproduced by Cisco and is a Cisco issue. Cisco TAC recommended upgrade of VManage to 18.4.5