Manual Focus problem

Hey guys,
So i bought Canon EOS 650D with 18-135mm STM lens last week,and I must say,I'm pretty impressed.
The thing is,I encountered yesterday was,at Manual Focus mode,both on video and still,after about 15-16 seconds,MF just doesn't work anymore.When I turn the ring in both ways,nothing happens.When I try to switch to the other mod,it usually encounters the Err 01 "communication between the camera and lens is faulty clean the lens contacts".I cleaned both,lens and body contacts with with a cotton pad and a drop of alcohol,turn it on,and after few seconds same thing happens.
Also,there is absolutely no problems with AF.AF works like a charm,and never malfunctioned.I was thinking it could be those wires in lenst (I can't exactly remember their name) that people suggest to replace when Err 01 appears,but then I figured,why would MF work for the first 15-16 seconds then?And yes,I can zoom in,and out and focus for the first few seconds,because I was reading that with some lenses problem can occure at specific focal lengths.

And yes,MF is very important for me,because I will use my 650D for video alot,and with,well not perfectly fast autofocus,I have to focus with MF.

Thanks for reading,and I would really appreciate any help.