There are a number of issues with simply re-adding your speakers to the new app. The new app lost my Beam system but not the Arc. I will save you a LOT of pain and say to contact support through Chat or Phone. I’m pretty good at troubleshooting but Support can get a hold of your configuration through their cloud, review diagnostic data and generally do things you don’t have access to. 

A 20 min chat session with support solved my very similar issue.

I've been experiencing some frustrating connectivity issues with my Sonos speakers lately. While I can initially connect to them through the app, at random intervals throughout the day, the speakers lose connection on the app interface, although they continue to function. For instance, currently, I can play music on all speakers, but I'm unable to adjust the volume for my Beam. This issue seems to toggle between different speakers like the Beam, Era 100, and Roam. The only solution I've found so far is to restart my entire WiFi network, which is quite inconvenient.