Not sure if this helps anyone, I have noticed that this problem occurs when the extended monitor switches side, as Opera opens up where it was last closed, so like me at work my monitor is on the left of my laptop, when I go home my monitor is on the right of my laptop, so opera still opens as if there is a screen on the left, I usually just use display settings re-arrange the screen so 2 is on the opposite side, drag opera onto my laptop screen and then go from there