Confounding the issue is that my phone had “Motion & Orientation Access” disabled in Settings and my test case didn’t work until I enabled it. At the same time, your visionscarto.net test case worked on my phone irrespective of my access setting. Do you know how aframe detects device orientation/motion?
Since iOS 12.2 devicemotion comes disabled by default and the user has to enable manually. devicemotion is also not available in cross origin iframes. That’s explain the behavior you see. The allowvr attribute won’t work in mobile devices.
My use case is not towards the public so toggling a setting is not a problem
I’ve had a mixed success with Safari (once the setting was on), where the menu disappeared when I:
opened the AFrame in vertical mode,
double clicked to switch to another app
turned the phone to horizontal mode
came back to Safari
It’s not working consistently. Plus, sometimes AFrame loses track of the dimensions, and a fragment of the left image goes into the right eye. (This might be related with the dimensions of the container div, I’ll investigate more.)
On Android it works perfectly on the first try :-/