I'm introducing someone with an iPhone 6 to VoiceOver and to Siri. We've set up the triple-click Home shortcut to turn VoiceOver on and off. I also wanted her to be able to use Siri to turn VoiceOver on and off for times when she found it difficult to perform the triple click of the Home button. But when we instruct Siri to turn VoiceOver on or off, Siri reports that it has turned VoiceOver on or off, but hasn't actually done the job. The status of VoiceOver remains unchanged. I haven't seen this behaviour before and I just tried another iPhone 6 on which Siri was able to control VoiceOver. Both iPhones were running iOS 12.3.1. Does anyone have an insight into what might be causing this behaviour, please? We have power cycled the phone and this had no effect.