No transactions added on import to Quicken

I'm trying to convert a CSV file containing credit card transactions for a particular period, so they can be imported to Quicken for Mac (Quicken Version 6.5.3, Build 605.42687.100 / Late 2013 iMac, macOS 10.15.7). The resulting QIF file appears to successfully import to Quicken, but no transactions are actually added in Quicken. I've tried resaving the file as a CSV from excel, as well as from WordPad, and have tried various mapping options for date format etc, but the result is always the same. Can you help?