My guess: the problem only happens if you have a new Tello with Firmware 01.03.33.01. If you already did an update you won‘t have a problem with the newest one..
I have the same problem. I‘m stuck to the Download-Screen.
I tried it on the following devices: iPhone XS, iPhone SE, iPad Pro, Moto G 1. Gen.
I even installed 1.1.2 - the download did still not start...