Testing on the iPhone 6 results in similar behavior to the iPad Air. The buttons at the top of the Add Group page (X and Save) are VERY badly implemented. There is no feedback with hitting them and after MANY tries, I finally had something happen with the save button only once. It saved the group but going back in to edit it results in the same unresponsive buttons again. The 'X' button just plainly does nothing, ever.
A possibility why your testing hasn't show this is that you are testing with very short Group names. Try a real-world test with a longer group name (long enough to take up two rows on the top panel. You will see that the buttons are hidden behind the Group Name element. This is probably why the buttons are not functioning properly.
As far as the Racetracker not getting any attention from your developers, what is the point of this app if not to use the Racetracker to run races? Trappy at TBS is telling everyone that you will be supporting direct interfacing with MultiGP's scoring system and your app will allow multiple Racetrackers to connect to a single IOS/Android device and run lap and lap/time based races (not just time trials for individual pilots). When is THAT going to happen?