Edit. I can’t read. Hold on. 

I suspect that the icon for S2 is over one screen, and not on your “home” screen. Try swiping to the left to access the next screen. 

Hint: the S2 app icon is ‘sand’ coloured.

Laugh. That’s a pleasant description.  :)

Yeah, well … 

That’s the official name of the color too :)

And it’s just called Sonos, there’s no S2 in the name of the app.

Where’s the “snort in derision” emoji? :)

No go.  “Sand” S2 icon no where, yet found and launches in a search.  Sounds like a phone issue if no one else experiencing this.  

Odd. I’d certainly try a full reboot of the iPhone. I’ve never had a missing icon to an existing application on any iOS device since they were released. Although I will admit the whole ‘page 2’ thing had me confused for a while. 

The icon’s not been accidentally swept into a folder?

Not in a folder or on screen.  Rebooted.  Never hd this happen. Should I just delete the S1 app which does show on the page?

Same problem here.  Downloaded the app but the icon is not showing up anywhere on my iphone.  Searched all my screens of icons, looked in folders, did a cold restart of my phone. 

I can get to the S2 App via a search or when I click on Sonos S1 it asks me if I want to load S2 but I cannot see the S2 app anywhere.

I’d try deleting the app, as well as the S1 app, and then rebooting the phone. Once the phone has rebooted, try a fresh download from the Apple store of S2. Make sure when you run it, you “connect to existing system”. 
My guess is something in the install process broke while setting up the icon, if it isn’t on the page to the right (swipe from right to left on the ‘home’ screen).

I have exactly the same issue on my iPhone 

It’s hard to delete the app when there is no icon for it.  I did manage to delete it by going to Settings, iPhone Storage and then scrolling through the apps to find S2.  Once found I selected it and selected Delete App.  I then went to the app store and downloaded it again (might not be a bad idea to delete a few unused apps and reboot before reinstalling) and it worked. 

I’ve never had an app that acted like that.  Don’t know if it’s a Sonos issue or the latest iOS.

Hard to tell. With so many other iOS users out there who have downloaded it, and had no issue, your guess would be as good as mine, I’m just happy it worked for you. 

I have seen this happen when developing apps, and using Storage to nuke it is the work-around. Not sure how a Store download can cause it though.

Don’t worry, the icon is vile - you’re not missing much!