I believe the "artifacts" you are talking about are just the zebras, which is normal.
The problem im comming across though is, that ettr measuring sometimes just wont really work. I have set it to be on the "set" button and when i press it the mirror goes up and back down again immediately. pressing and holding the set button then often does the trick.
in average it works like every second or third try. After the mirror snaps back up, take a normal photo and it will be exposed to the right.