android chrome VR icon

recently the VR icon that allows you to switch to VR mode on a mobile device has disappeared from the menu when viewing my tour with a chrome browser on android.
it still appears with different browsers and when viewed on the desktop with a computer.

can anyone advise what may have happened and how i might correct this problem please.

even more strangely the menu does appear (using chrome android) with the same tour but when hosted on a different server. the only difference is that the one where the menu button is invisible is launching from a server via an .htaccess file.

any help welcome
thanks.

thats interesting.
so would the consequence of that be that the VR button is no longer showing (in a non https environment on a mobile) do you think ?

thanks for your reply Klaus and sorry to push for your reply, its just that i have a cliet waiting for my response and i wouldnt want to advise my client to buy an SSL certificate only to find the VR button still didnt appear afterwards.

So the consequence of the chrome update and no gyro support on http would be that the VR button is no longer showing on a mobile then ?
The host where this button is missing is http and the one where it is still visible is https.
but then the VR icon does still appear on the http site when viewed on desktop.

So the VR button would disappear on a mobile when there's no gyro support ?

thanks for your help on this,
Simon.