Import completes without warning but doesn't import records where data to be imported uses "Yes" or "No" instead of "1" or "0" for fields of CiviCRM type "Yes or No"

This error occurs when you try to import a record into CiviCRM that has a field which contains "Yes" or "No", matched against a CiviCRM field that is of the type "Yes or No".

The Import is reported as having completed successfully but the record will not actually be imported.

Changing a "Yes" to 1 and a "No" to 0 resolves the issue, but the Import engine should recognise "Yes" and "No" in all case variants and do this for you.