UPD: for Unity version 2017.1.5f1
Just checked with another version. There is the same issue too, but slightly different which is weird.
If I click on the particular frame with my touchpad(not tablet), frames won't change unit I draw one line and after that -- same behavior.
However, with this, I at least can calmly draw one line, heh.
I upload another video with it: google drive