That’s pretty damning, isn’t it? I bet the problem is somewhere in FmodAudioManager::audio_3d_set_listener_attributes(). 
Looking at that function now, it is only calling a method on the global FMod _system object, but that could be trouble if it gets called from separate threads, or even if it is only called from the main thread but there is something else FMod-related going on in another thread simultaneously.
I think all of these calls into the global _system object need to be protected with a mutex inside the p3fmod layer. I’ll try to make this change in the next few days, and we can see if it helps your crash.
David