Just opened and set up a brand new IPad Air 2 yesterday. I used a smart cover to put it to sleep yesterday. I too was worried when today, all of a sudden, the volume icon which I had see yesterday, SUDDENLY DISAPPEARED when I was setting up my "sounds"...... yet the 2 side volume switches worked!!! I had downloaded several audio books last night before I closed the cover for the night and the volume toggle switches and icon worked then, but no volume icon this morning!!!
A Google search brought me to this site.
FYI, My IPad Air 2 has the latest 9.3.1 version. Someone mentioned passcodes etc. I have an IPad 2, IPad 3 and IPad Air 2. Here's what I found.
My IPad 2 IS NOT UPDATED to the OS 9 version and It's still running 8.4.1. I DO use a cover to put it to sleep, I DO NOT USE A PASSCODE. The volume icon appears using the side toggle switches after long "sleeps" and after opening the cover.
My IPad 3, IS UPDATEE to version 9.3.1. I use a cover to put it to sleep, I DO NOT USE A PASCODE. The Volume icon DOES APPEAR when I use the side toggle switch after opening the cover and after long "sleeps"
On my BRAND NEW IPad Air 2 is running version 9.3.1. someone suggested either using the RESET or physically turning it OFF and back ON. I did the latter AND THE VOLUME ICON DID REAPPEAR. For how long it will stay there I don't know. I've closed the cover and opened it and the Icon does show up again. So I don't know what the deal is. Is it the IPad model itself in combo with a sleep cover? Is it length of time it's asleep? Why does my IPad 3 with the same OS version as my IPad Air 2 work, but the IPad Air 2 gets quirky?
After turning If "OFF AND ON" , I did change the AUTOLOCK setting ( General > AUTOLOCK ) from NEVER TO 15 MIN on the IPad Air 2 . So far my volume icon is appearing after using my sleep cover.