If the report is run ad hoc in Performance report designer all the needed data is showing up but when it is generated via scheduled report some of the data is missing.
Release : 20.1
Component : UIM - UMP_REPORTSCHEDULER
Observed that there are duplicate entries for the source one with hostname and other with ip address for the the same device in s_qos_data table
The report scheduler was populating data from the ip address source entry which had no data collected
Deleting this duplicate record from database using SLM portlet resolved this issue