I’m having the same problem; unable to add the ones to the surround, could only create a stereo pair and now I cannot remove them from the pair. 

Same issue!!! One SLs removed from surround after app update. Could o le get to work as stereo pair and now I can’t remove that living room system from my system to set the one sl up In Surround it won’t recognize the speakers now. So pissed off with Sonos messing things up system worked perfect before new app

After talking to support, the update of my Sonos Arc solved my issue with the pair of Ones. After the update of Arc I could remove the stereo pair and man them surround speakers instead. 

I have sort of the same problem. 
 

I currently have two ERA 100’s as a surround pair with my ARC. Today I bought two ERA 300’s and want to change them with my ERA 100’s, but it is impossible to remove the ERA 100’s as the surround speakers, I keep on getting error messages “Check network and if they are ON etc enz”

My system is all up 2 date?!

How can I solve this?!

I have the same issue with a stereo pair of Era 100’s which I just set up for stereo music and to stream the audio from my iPad. After the app update the stereo par no longer shows up in the AirPlay list. I tried to delete the stereo pair to see if that would correct the issue but I can’t delete them.  I don’t have any soundbars to update and the app says everything is up to date.  If I start music from the app or from the Alexa voice option the pair operates normally but I can’t stream to them from my iPad.

This is ridiculous

I'm experiencing the same issue! After the app update, one of my One SLs was removed from the surround setup. I could only get it to work as a stereo pair, and now I can't remove the living room system to reconfigure the One SL in surround mode. The speakers are no longer recognized. I'm really frustrated because everything worked perfectly before the new app update. Sonos has really messed things up! 

This is happening to me but I don’t get an error message. I try and press the button and it will not work… just 3 play:1’s. 2 in a stereo pair and can’t get them apart now…