Why is a Report Data source stops building and always Needs manual rebuilding

A datasource for multiple reports stops building and needs manual rebuilding to work.
Today I found the report data count to be around 9k and It is not incrementing, so I rebuild it and after 10 mins the datasource is 44 K.
Before rebuilding

After rebuilding

This kind of problems happend on multiple datasources on our server and I have to always manually rebuild it periodically.
Any fix for this problem?

Under normal operation, data sources are populated by the pillowtop process, my best guess would be that that process is stalling or failing in some way. I’d check that that’s online and check the logs to see if it reports any failures.