Here is a "fun" one, new to V1.2x:
If your pano is displayed in a div with position (fixed, absolute or relative) AND you have a background image, the pano displays fine on all browsers on all platforms. BUT switch into VR Mode on mobile browsers (ed: iOS only) and only the background image displays, not the VR pano, which disappears from existence. This doesn't happen in mobileVR (headset) browsers or in FakeVR mode on the desktop.
Example: tdf360.com/test/thumbs/tour.html
Very, very weird...and irritating. Any ideas why this is? Can you fix it, Klaus? (Actually I am sure you can. You can do almost anything.)