I've further findings on this issue, upon troubleshooting another report having similar problems. The PDF report is available, but "No results found" is shown for each panel. On the other hand, test run is okay.
It turned out that all the knowledge objects (macro, field extraction, events, tags etc) used in the reports must be given global permission, otherwise there will be no result returned during the scheduled run. I suppose the scheduler somehow is also subject to the access control in this case.
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