Unable to update plot in app designer

I am trying to update a plot in app designer within a for loop. The plot is only ploting the last result of the loop after the loop is finished. I am using a push button to start the loop. I am using drawnow but it is not working. Here is my code. I am using R2019b. Please help in out from this. Thanks.

[Walter Roberson]

I do not know the reason for the problem at the moment.

I would, however, suggest that it is typically better to create the line objects before a loop, and then update the line objects within the loop, instead of calling plot() each time.

L1 = plot(app.UIAxes, nan,nan);
L2 = plot(app.UIAxes, nan, nan, '.g');

for i = 1 : n
    %stuff
    L1.XData = A; L1.YData = B;
    L2.XData = x1; L2.YData = x2;
    drawnow();
    pause(0.5);
end

[Saurabh Chaudhary]

Getting error "invalid or deleted object". When I added "hold(app.UIAxes,'on')" after the "L1 = plot(app.UIAxes, nan,nan);", then the error is not coming but the problem is same the plot is not updating like previous. When I click push button it is showing only the last configuration.

[Saurabh Chaudhary]

I do not know the problem, but I increased my system RAM then the old program is working fine. But thank you so much Walter Roberson for the reply. I have learned a new thing from your answer.