Hi @Diana Shiny ,
while permissions needs to be verified, I don't thing that this is the cause here. Permissions are static in this case, meaning that it will either work or it won't. Still if you want to ensure you have configure the proper permissions, please do this here:
SCOM: Configuring sudo Elevation for UNIX and Linux Monitoring
What you can also do is check the Audit logs on some of your AIX systems, if there is an issue with the sudoers config, they should contain related records.
What you need to also do is to compare the time interval, when there is no data collected with the overall health of the systems - are those reachable and monitored, are there any other related alerts?
What you can also is to check whether the data is present in the DB at all:
Just run the performance data query and verify if there is data for the interval in question. If not there is some problem with collecting the data indeed, if Yes, there is most probably some issue with your report.
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Regards,
Stoyan