Sound notifications stopped working on iPad, iPhone, iPad Pro

Sound notifications stopped working, all of a sudden. It’s happening on any device I try - iPad, iPhone, or iPad Pro. Motion is recorded, but I do not get any audible sound. That means I discover the clips hours later. Plus, most of my camera connected to electricity. Only 2 cameras on batteries. Any suggestions?

I’ve checked:

  • WiFi signal strong
  • cleared cookies and cache
  • notifications turned on
  • 6.2.13 version
  • all cameras “armed”
  • restarted iPad