[Q] Where has my Priority Notifications option gone

OK, I may have done something silly or not and I am not sure if it is related to the latest S/W upgrade or not but today I noticed that I no longer get the options for 'None', 'Priorty' or 'All' on the sound slider (see attached)

It was definitely there after the first lollipop upgrade and it's definitely there on my Nexus 9 so is this part of Sony's modifications or have I done something stupid?

Thanks

Attached Thumbnails