The X-Run (of the device side) rises and there is no sound

MacOSX and iOS
1

HI,

When the X-Run occurs on the device side (managed by juce_mac_CoreAudio),
there is a phenomenon where only the X-Run goes up without sound.

Is this intended?
(FYI - The X-Run doesn’t raise on my processing side. CPU Usage (actually looks like Real-Time Factor) is around 20-30%.)

I don’t know the logic of the device side, but it doesn’t happen when I comment the code like below.
modules/juce_audio_devices/native/juce_mac_CoreAudio.cpp +1876

    void xrun() noexcept
    {
//        for (auto& d : getDeviceWrappers())
//            d->sampleTime.store (invalidSampleTime);

        ++xruns;
    }

Can anyone explain this?