Strange behaviour with impoint()

I need to manually mark data points that weren't detected by my algorithm. So I have been trying to use impoint() and when it works, it's great.

The problem is that, occasionally, when I click anywhere in the plot, the marker jumps a centimetre below to where I have clicked. And it continues to jump around everywhere you click. You can never actually double-click the point to confirm, because it just jumps away from your cursor like a game of tag.

This occurs very inconsistently and I can't figure out what part of the script is relevant to the error, but here's the part immediately surrounding impoint().

       plot (breath)
        hold on
        for i = 1:numAcc
            plot(inhale{i,2},breath(round(inhale{i,2})),'rx',inhale{i,1},breath(round(inhale{i,1})),'gx')
        end
        set(gcf, 'Position', [0, 250, width, 600])
        corInhaleBegin = impoint(gca,[]);
        getPosition(corInhaleBegin);
        accepted_pos1 = wait(corInhaleBegin);
        resume(corInhaleBegin);
        correctedBreath(corCount,:) = {accepted_pos1};
        close

Edit: When I comment this line

set(gcf, 'Position', [0, 250, width, 600])

the problem goes away. Does anyone know why this is? It saves me a lot of clicking and dragging if I can have the window appear at this size so I regret having to comment it.