Import Activity Sometimes Ends in COMPLETE_WITH_ERRORS With No Error Report — What Could Cause This?

Summary:

We are seeing an intermittent issue with Import Management (object: ChannelBatchTransaction).
Occasionally, an Import Activity ends in:

Status = COMPLETE_WITH_ERRORS

but no error report is generated, and the Import Activity does not show any meaningful details about the failure. When we re-run the same file in a new Import Activity, it completes successfully.

What could cause an Import Activity to fail intermittently with COMPLETE_WITH_ERRORS and no error report, while the same file succeeds in a later run?
Are there known reasons or best practices to avoid this behavior?

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