Hello, it happens randomly to me too after I export a video composition: * thread #7     frame #0: 0x000000020ce9ab48 libsystem_kernel.dylib`__psynch_mutexwait + 8     frame #1: 0x000000021d2fd150 libsystem_pthread.dylib`_pthread_mutex_firstfit_lock_wait + 84     frame #2: 0x000000021d304310 libsystem_pthread.dylib`_pthread_mutex_firstfit_lock_slow + 248   * frame #3: 0x00000001d195856c QuartzCore`CA::Context::commit_transaction(CA::Transaction*, double, double*) + 388     frame #4: 0x00000001d198d5ec QuartzCore`CA::Transaction::commit() + 652     frame #5: 0x00000001d19ddab4 QuartzCore`CA::Transaction::release_thread(void*) + 228     frame #6: 0x000000021d2fcbd8 libsystem_pthread.dylib`_pthread_tsd_cleanup + 620     frame #7: 0x000000021d2ff674 libsystem_pthread.dylib`_pthread_exit + 84     frame #8: 0x000000021d2fc0e0 libsystem_pthread.dylib`_pthread_wqthread_exit + 76     frame #9: 0x000000021d2fbe80 libsystem_pthread.dylib`_pthread_wqthread + 424 main thread is  thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP   * frame #0: 0x000000020ce99b48 libsystem_kernel.dylib`mach_msg2_trap + 8     frame #1: 0x000000020ceac008 libsystem_kernel.dylib`mach_msg2_internal + 80     frame #2: 0x000000020ceac248 libsystem_kernel.dylib`mach_msg_overwrite + 388     frame #3: 0x000000020ce9a08c libsystem_kernel.dylib`mach_msg + 24     frame #4: 0x00000001d19b1a14 QuartzCore`CA::Render::Message::send_message() + 84     frame #5: 0x00000001d1b8e090 QuartzCore`CA::Render::Encoder::send_message(unsigned int, unsigned int, unsigned int*, unsigned long) + 940     frame #6: 0x00000001d195a684 QuartzCore`CA::Context::commit_transaction(CA::Transaction*, double, double*) + 8860     frame #7: 0x00000001d198d5ec QuartzCore`CA::Transaction::commit() + 652     frame #8: 0x00000001d19768cc QuartzCore`CA::Transaction::flush_as_runloop_observer(bool) + 88     frame #9: 0x00000001d295db44 UIKitCore`_UIApplicationFlushCATransaction + 52     frame #10: 0x00000001d2aab740 UIKitCore`_UIUpdateSequenceRun + 84     frame #11: 0x00000001d30f2fd0 UIKitCore`schedulerStepScheduledMainSection + 172     frame #12: 0x00000001d30f219c UIKitCore`runloopSourceCallback + 92     frame #13: 0x00000001d0371f54 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28     frame #14: 0x00000001d037e32c CoreFoundation`__CFRunLoopDoSource0 + 176     frame #15: 0x00000001d0302210 CoreFoundation`__CFRunLoopDoSources0 + 244     frame #16: 0x00000001d0317ba8 CoreFoundation`__CFRunLoopRun + 836     frame #17: 0x00000001d031ced4 CoreFoundation`CFRunLoopRunSpecific + 612     frame #18: 0x000000020961a368 GraphicsServices`GSEventRunModal + 164     frame #19: 0x00000001d27fb3d0 UIKitCore`-[UIApplication _run] + 888     frame #20: 0x00000001d27fb034 UIKitCore`UIApplicationMain + 340     frame #21: 0x00000001d8deb308 libswiftUIKit.dylib`UIKit.UIApplicationMain(Swift.Int32, Swift.Optional<Swift.UnsafeMutablePointer<Swift.UnsafeMutablePointer<Swift.Int8>>>, Swift.Optional<Swift.String>, Swift.Optional<Swift.String>) -> Swift.Int32 + 104     frame #22: 0x00000001023da5d0 StickerTune`static UIApplicationDelegate.main() at <compiler-generated>:0     frame #23: 0x00000001023da558 StickerTune`static AppDelegate.$main(self=StickerTune.AppDelegate) at AppDelegate.swift:13:1     frame #24: 0x00000001023da654 StickerTune`main at <compiler-generated>:0     frame #25: 0x00000001ee984960 dyld`start + 2528 Does anybody has a workaround for this? It's extremely frustrating as the whole UI locks up! :(