I have 5 amps (one current generation) and one old soundbar, since the App major update, I have not been able group them. I get the “Unable to Connect”.
For a brief period, I did have one update for all the units and it worked for a very short period. Then it failed again for months. Since 3 units are in one open area, it is very important to be able to group them.
I tried power cycling all the units, no luck. They are all upto date for the software. If it prolongs much longer, it would have to replace all the until with alternatives. And not get any additional Sonos in the other rooms.