Could it be that bleeding with Qlaira does not occur?

When taking Qlaira, bleeding usually begins on day 26, the day you take your second dark red tablet, or over the next few days. Bleeding is caused by exfoliation of the endometrium under the influence of a decrease in the concentration of hormones. With a very thin endometrium, there may be no "material" to exfoliate. According to the Qlaira dossier: "The diaries kept by the women in the Qlaira clinical trial show that it is not uncommon for withdrawal bleeding to occur after day 26 (found in 15% of cycles)." Unfortunately, it is difficult to answer whether or not you will experience withdrawal bleeding. If all the tablets were taken correctly, there was no vomiting or severe diarrhoea and no other medicines were taken, the probability of getting pregnant is small, even if bleeding does not occur. The leaflet states that "If the expected bleeding does not occur twice consecutively or if the tablets have been taken incorrectly, this may indicate pregnancy. Contact your doctor immediately. Do not start the next pack until you are sure that you are not pregnant." I enclose additional information: https://www.gdziepolek.pl/produkty/65571/qlaira-tabletki-powlekane/apteki