I am using Windows 10 1703 x64.
I cannot reliably reproduce this, but occasionally, I will select some text to copy it or replace it, and then when I go to hit ctrl-c or ctrl-v, the text is no longer selected so I end up copying the entire line, or pasting into the middle of whatever I was trying to replace.
I am mainly editing Python files now so that is where I am seeing it. I will try to pay attention to see if it happens in other file types. I only thought of that possibility as I was typing this.