First Alert ZCombo Smoke\CO

Hi All, I have a few First Alert ZWave combo Smoke\CO units that are certifed to work with the Ring Alarm. These do work as when I burnt something in the kitchen my Ring was alarming on the base as well as my phone. What scares me though is that I took the batteries out of a couple of them (they are not hardwired) and Ring didn't notify me that they were offline. Is this a bug? Or does the Ring Alarm NOT monitor the devices to see the battery level? Or if they are even online?