This is an OBDLink firmware problem. The adapter locks up, stops responding to any commands from the app. Then app occationally crashes, which of course does not make the sitation any better. Or, the truth is, I have reported this problem to OBDLink for years, they have spent a lot of time trying to recreate the issue in their lab, but they can't. I honestly don't know where the problem is, but I know if I connect even a Windows laptop to the adapter after this happens, Windows also doesn't get any response from any command, even ATZ (reset). I suspect it also could do with the phone's bluetooth implementation, some phone brands are bad, some are perfect.
Some things to try:
- The OBDLink app has firmware updates, try that for starters
- Try to run less data through the app, don't always use the All tab but use the other premade ones, or create your own
With my equpment this only happens after recording CAN dumps for longer periods (usually 20+ minutes). Unless I do this I rarely see this problem, and I run the app literally 24/7 in the car for years. In my case the OBDlink loses power when the car sleeps, this makes it always boot fresh every day, you could check if your wiring harness allows this, if it doesn't you can move one pin on the car side to pull a 12v source that goes offline when the car is sleeping.