Hey everyone,
I was having the same issues. I speculated that it was an issue with the yellow, not-rendered line, but I too couldn’t get the Shift-Enter thing to work.
So I went up to the menu bar and clicked ‘Sequence’,
Then I clicked ‘Render Entire Work Area’,
and after it did that, the whole line was green and
the footage wasn’t pixelating.
Hope this helps anyone else that comes to this thread!
((Note there are two options which look very similar.
‘Render Effects in Work Area’ and ‘Render Entire Work Area’,
make sure to click ‘Render Entire Work Area’.))