The Failure Modes Not Detected section of the Non-Detected Failure Modes table in the Detection Coverage Report (pictured below) lists the failure modes that are not members of the coverage of any of the tests in the given detection sequence, are not explicitly excluded from the coverage of any of those tests, and are not detected by any of the other tests in the sequence.
Note: the number of columns that appear in this section of the report is based on the size of the listed failure mode names (the longer the names, the fewer the columns).