You might want to consider backing up your device and then restoring it as new via iTunes.
Thanks.
I did the restore from back-up and thought that fixed it.
It was locking and dimming just fine.
Then I noticed something.
After triple clicking home to access "AssistiveTouch" options to -MUTE- and then triple click home button to disappear AssistiveTouch my i5 it would no longer Auto-Lock nor Dim.
Even after locking the phone and hitting the home button to wake it up it would stay on.
Auto-Lock stopped working.
I powered down the phone and turn it back and guess what?
Yes, the Auto-Lock function was working properly again.
I triple clicked home button for AssistiveTouch, MUTED my phone and again the Auto-Lock did not work.
I performed a Soft & a Hard Reset and again after performing this Auto-Lock would work.
After each reset I would AssistiveTouch to mute my device with the same problem of no Auto-Lock after.
Frustrating
I hope this is something that can be addressed in a soon to be released update
I use and rely on this feature working properly on a daily basis.
EDIT: I just realized you suggested "RESTORE AS NEW" and not what I thought I read as From Back-Up haha Thanks again