Thank you for your reply, MMaynard.
I had done all checks you suggest, apparently these are the first logical thoughts come to mind.
The "Status’ tag is string tag. And it may take 5-6 different values, so it cannot be just 0 and 1.
The funny thing is I have another 8 same reports for same type machines, and all run normally, no quarantined items generated.
I was thinking to delete the transaction group and the report and start all from scratch.