To : uliwooly
Yes, I'm using Google Chrome. So far of my knowing...tapping and sliding unsensitive / unenabled with apps like built-in Calendar, Gmail, Google Keep, Yahoo Mail (installed by me) at times so need to tap and/or slide more than twice or so, real hard with the finger). Whereas, certain websites which have a menu / options icon that required to tap or slide from left also have had this issue.
To : Phy
I'd done Diagnostics twice before and after the bug but everything appeared to be ok. It can't bring any help.