What version of the framework are you using within the AT?

It's certainly working fine for me if I download the latest version of the framework using the Adapt CLI and build from that.

One possible source of the problem was that we recently had to change lots of clickable items in the framework and core plugins from <a> to <button> to make VoiceOver for iOS work properly - including the back button in the navigation. If you have anything that's still set to look for the <a> version of the back button, it's not going to be able to find it. Conversely, if your theme still has the back button has <a> in the template, the latest framework code is going to be unable to target it.