I have today paid a visit to the local Apple store to try out my new tour on their various devices.
All worked well except the iPhone 6 Plus. There definitely seems to be a problem with this device in landscape mode.
I initially thought there might be something wrong in my code, but the same things happened with the example panos on the krpano website.
Opening the Corfu tour in Safari while holding the phone in landscape mode resulted in the pano displaying only a strip of the image, complete with the pano's own control bar, but at the top of the screen immediately below Safari's menu bar, with the rest of the display blank below it. I then rotated the phone to portrait mode and all was OK. I turned it back to landscape mode and then the krpano control bar was off the bottom of the display and not visible. Dragging upwards brought it back onto the screen. Dragging downwards then moved it half on and half off the screen.
Also, there were times the screen failed to respond to touch while in landscape mode, but again all was OK in portrait mode. I tried the bbc.co.uk website and none of the links on that would work in landscape mode, so it seems the problem is not limited to the display of panoramas.
With an Apple technician in attendance I tried two other iPhone 6 units and had similar results, which left him baffled. The problem appears to be limited to the iPhone 6 Plus. The normal iPhone 6 was OK.