iPad going to sleep after 12.0.1 update

Hi all,

My company uses iPads of varying models as conference room schedulers. The tablets are housed in metal enclosures and kept constantly powered via both AC for some units, and POE power for others. After updating these tablets to 12.0.1, we're finding that many of these tablets are going to sleep despite having Auto-Dimming off in accessibility settings and setting Auto Lock to "Never". We have Guided Access turned on, and cannot seem to find out why these tablets are going to sleep.We're wondering if there was a change in the recent update that prevents tablets that are constantly powered to automatically sleep as some sort of battery management?

This is an issue for us as we would like the tablet screens to always be showing. Any help here would be great!