Somehow, suddenly one of my many  KASA TP- LINK  HS 105 Plugs started turning OFF my living room lamp every night at 10pm.  I checked the plug schedule and no 10:pm was shown.  I did a factory reset. STILL turned off at 10pm.  Changed schedule... still turned off at 10:00.  REPLACED THE PLUG.  Still turning off at 10 pm.  Changed outlets. Still same problem.  Even KASA customer support couldn't figure it out.   After 2 months of this,  I thought of going to my ALEXA APP,  and checking if my KASA ENABLED SKILLS, to see if the skill needed an update.  Here's the steps... OPENED my ALEXA  APP >  click at the bottom the where it says "MORE > now click  "SKILLS AND GAMES" UNDER SEARCH ALEXA SKILLS  I Typed "TP LINK KASA SKILL" . It listed several choices.  I clicked on the first one... the blue house in the bubble..."TP-LINK KASA".  

This opens the TP-LINK KASA SKILL Now click on "SETTINGS". Under" ADVANCED SETTINGS", click on " MANAGE SMART HOME DEVICES.  Now find the name you gave the plug that's acting up. 

This is where, for some UNKNOWN REASON, Alexa set up a ROUTINE to shut my lamp off at 10:00 pm every night..... OVER-RIDING what was listed in my phones Kasa Schedule!!!!  I deleted the routine and BINGO... PROBLEM RESOLVED.

 I suspect that  the Kasa TP-Link plugs or outlets that have mystery unscheduled on and off problems, you'll find ALEXA somehow setup a routine for the Kasa SKILL, and you need to go to your ALEXA APP, NOT THE KASA APP, to resolve it..  

hope this helps others...