The Kids Corner Trick only gave me temporary relief... and then the problem returned... and then temporary relief...
I don't have "The Live Lock Screen App." I have used LockMix, does that count?
I've done soft reset, hard reset, Reflash with Software Recovery and not use LockMix... Still came back.
I also noticed it was only an issue AFTER using stock Music or Video App with media stored on SD card. Do these symptoms line up for anyone else?
My Theory: The stock Music and Video Apps don't let go of the file even after the App closes and the RESUME is a null background process trying to access the file off the SD card for an App that is closed. "Resumes" always came after accessing media from SD.
I've switched to ModernMusic for audio and MoliPlayer for video. While MoliPlayer plays like every audio and video format I can't get it to play under sleep mode... ModernMusic does that.
Just flashed the phone back to stock for the second time (after fiddling uselessly with Kid's Corner with no remedy several times). First use of Music and quit, doomed me to resume screen. After moving off the stock players, I've indulged heavily in music and lightly in vid; turned the phone on; put it to sleep; normal motions; more media; more motions; more sleep/wake... No issues today.
Lord I hope this solves it.