This happens to me too, constantly. The feed will be playing fine for
some time (some time it's minutes, hours, etc.. sometimes it's literally
1 minute), and then just cut to a screen that says "Camera feed is not
available". I have to go back, wait ...
Yes, I'm able to use a voice command to bring up the cameras
individually. I don't have a Nest Hub Max, but I do have Gen 1 and Gen 2
Nest Hubs and it works on both via voice.
Also, I found that slightly faster than going to Rooms, finding the
correct room, and then finding the camera in the room, a workaround
is:Go to the Security Tab. The right half of the screen shows a camera.
There are left/right buttons on the bottom...