Have been experiencing issues with the sonos app for a while. Ultumately ive switched to setting up a Sonos HTTP API docker container to solve my own issues. So that’s a route you can consider to take, but only if you have some experience with setting up docker containers.
The other option you can consider is to restart the app first through the same flow. This can be done by enabling the power user settings (settings → experiments → power user).
I have no problems with the Sonos app. The only bug I know of is that the “plays/doesn’t play” function doesn’t work.
Could the wifi be causing the problem? Do the speakers have a fixed IP?