Acrobat Reader for iPad in Guided Access mode

Hi there,

Recently I installed a bunch of iPads with Acrobat in Guided Access Mode (locking it down to a single, full screen PDF file.

It was working fine until recently, when now people can single press on the screen and access the top menu bar which allows them to edit the PDF among other things - obviously not what I want.

I'm not sure whether this is an issue with a recent iOS update or an Acrobat update, but it was not happening before. Is there any way I can ensure the PDF stays in full screen mode with guided access?