2017 to 2018 LTS - any major changes (mobile)?

Having upgraded a project from 2017 to 2018 (LTS) I have some issues with touch input ‘exiting’ UI controls when it shouldn’t. It is a complex issue which is not seen on desktop & unity remote, but so I was wondering if there are any change notes or things to look out for in upgrading between 2017 & 2018?

In case anyone uses cursor lock - note that ruins the touch UI system and causes premature ‘exits’ like this to happen! (thanks NGUI in this case!)