is there any way i could get access to other fenix runtimes to try out? I know the version you're using is beta so maybe if I could try a different version whether newer or older maybe that would help.
I remember when you first said you were using a new fenix and i tried out the runtime with some other games and some other games definitely had problems with the runtime. also the new runtime seems to use the mmu hack which can at times make programs unstable and prone to crashing.
so as you mentioned before its probably an issue with the fenix runtime and not your code if its an issue at all for anyone else.