Here is the reply we sent yesterday via email:
Please make sure you are using the most up to date version of the app which is 5.4.5. You are using 5.4.3. We are continually fixing things on our new virtual sticks controls for supporting your aircraft. Also, the use of the iPad mini 4 is likely not going to be great using the virtual stick controls which rely on having fast response times and maintaining a solid connection. We have been recommend the use of an iOS device with an A10 processor or better for the last 2-3 years. The iPad mini 4 has an A8.
There is clearly something weird going on with your flight after takeoff so fix these other issues and we can go from there.