MODEL: Losing Audio (Ableton - iTunes- others combined)

I am sometimes losing my audio signal when using Model as an interface hooked to MacBook Pro with Ableton and I use iTunes and then say Youtube.

I feel like when I use more than 1 or 2 I lose the audio interface signal and can’t regain it regardless of the setting on MacBook or Ableton.

Is there some auto feature or control I am not aware of that you need to configure to avoid this?

I know it is the Model interface signal I am losing and not anything else because the other signals coming from hardware or other means are being fed into the same mixer are getting through to the recording iPad no problem.

If I unplug the USB from MacBook and plug back in, it will work. So, just not sure what happens.

Thanks in advance.