The Cook Programs and Recipes in the Weber Connect app have been tested extensively, with 70 years of knowledge to back that up, in order to provide the best possible results. Flip notifications are dependent on the internal temperature of the meat which is transmitted through the temperature probe. It is always a possibility that the probe has been inserted incorrectly or is too close to bone or the grill grates. Try reinserting the probe and allow the program to carry on.
For programs that do not require probes, flip notifications are dependent on time. These time suggestions have been tested thoroughly based on USDA guidelines. Always remember to rest your food at the end of a grilling session for best results.