It might be beneficial to determine if the people with the larger phones are having a problem too. Or is this problem limited to just a few users that have congregated here because of the problem they are having and they all have the "smaller" iphones. Like I said, inadequate memory is only a remote possibility. But having to cycle things on and off sometimes points in that direction.
On another tangent, having problems with the DX8 and the STi points back to the TM-1000. As I understand it, the TM-1000 has it's own hardware, program and antenna. It only takes flight data and power from the Rxer and broadcasts the flight data and the other inputs' data (e.g. Engine temp, Rxer voltage, etc.). Then the DX8 and the STi have separate Rxers that individually "catch" the TM-1000's broadcast. So the DX8 and STi are operating independently of each other. The only thing common to them is the TM-1000. Is it possible to try a different TM-1000? Does repositioning the TM-1000's antenna make a difference? Are the various components to close to each other? For example:Are the DX8 and STi too close to the TM-1000?(e.g. the TM-1000's transmitter could be overloading the DX8 and STi's receivers, etc.)Are the DX8 and STi too close to each other?(e.g. the DX8's transmitter could be overloading the STI's Rxer) Are you near a large metal object? Is the data/power line to the TM-1000 intermittent? Is the AR 8000's power output to the TM-1000 intermittent (e.g. cable connections or intermittent cables, etc.)?
I had a weird problem with a heli tail rotor and could isolate it to a single component. After much chagrin, I started replacing things at the tail rotor's servo and worked my way all the way back to the ESC. There was an intermittent component in the ESC. Point being: Start at where you see the problem and replace things working your way back to the battery, one component at a time and then testing before you replace a second component. If you get all the way back to the battery and still have the problem, well, ... you have the proper spare components and you know there is most-likely software is the problem. Then it is time to lean on the programmer.
I kind of have to rule out the DX-8's software as mine is working very well with my TM-1000. I assume you have the latest DX8 software.