Loud notification from Nanit when phone is on silent? Why?

My phone just pinged to tell me that the breathing monitor wasn’t found like it normally does when I remove baby from crib, except this time it pinged despite my phone being on silent and woke my baby up? Why!

I’m having never ending problems with the Nanit. The app is so slow, the nightlight just failed to work and I had to reboot, it turns itself on and off sometimes so the white noise stops then comes back on again (baby wakes up). It’s just making everything so much more difficult and I paid over £300 for this item.