Why do I have failed files in the scan details of the o365 Securlet?
The failed column represents both non-recoverable documents such as deleted or locked files or files that are to big to scan as well as items also include files marked to wait and retry because the SaaS is busy (429 error).
The failed files column will fluctuate with a sudden increase of new files to be scanned or as files are deleted or modified.
Failed files are retried daily for 30 days. Files greater than 30 days will not be re-scanned. If you find a large number of failed files reported that have not cleared up over time, create a support ticket asking for detail regarding these files such as the number of non-recoverable files or asking for a re-scan of failed files >30 days.
A re-scan may not touch these files as only exposed file would be re-scanned and only for 30 days for email.
A feature has been requested to break down failed files in greater detail.