When our intrepid leader suggested putting three books up on promo at once I was not at all sure such an idea was a good one. When Amazon KDP failed to register any downloads we were both beginning to think the same. Then ... we checked the statistics for each book and saw that they were rising in the promo charts on a steady basis, not only in the UK, and .com but also in Germany and France!
All is forgiven intrepid leader, you were right! We ended the day with the comfortable feeling that lots of people now have three of our books. We don't know how many yet because KDP is still showing nothing! Oh, the wonders of modern technology!