Question about possible delay

Hi, we encountered a deadlock/severe delay. the stack is

__psynch_cvwait (in libsystem_kernel.dylib) + 8
_pthread_cond_wait (in libsystem_pthread.dylib) + 984
std::__1::condition_variable::wait(std::__1::unique_lock&) (in libc++.1.dylib) + 32
filament::FFence::FenceSignal::wait(unsigned long long)
filament::FFence::waitAndDestroy(filament::FFence*, filament::Fence::Mode)
filament::FRenderer::terminate(filament::FEngine&)
filament::FEngine::destroy(filament::FRenderer const*)

is there any possibility that the below condition is also waiting, so that the new created Fence would never signal. Besides, we did not call Engine::setPaused.
https://github.com/google/filament/blob/8d6e8b8b3cc741bfa9bcf01174208cc7199cb694/filament/backend/src/CommandBufferQueue.cpp#L151

Any other possibility of this wait?