Tried that - no joy. Obviously have some interaction going on that's breaking that app. I've read of others having a similar problem so we'll probably just hold out and see if a patch comes along. Thanks for replying.

Other apps rotate just fine. So far it seems only Google Search app is affected. I've uninstalled and reinstalled Google. Turned off and on phone. Upgraded to iOS 10.0.2. Still won't rotate in the Google app. Any ideas on further debugging?

Does this work for you?: iPhone 7plus, Google App search, click on web page result. Tilt phone to landscape and it doesn't change. Open page in Safari, landscape works fine. This scenario works fine on my 6S iOS 10.