Strange UI behaviour in App Designer

I am designing an app in App Designer but sometimes when I run the app the UI becomes broken (see first image) and I have to run the app again for the UI to render as intended (see second image). I have used the 2-Panel App with Auto-Reflow template to start designing this app. I'm not providing any code snippets as I don't know where the problem might originate from and because the problem appears even if I don't make any changes that affect the UI of the app.

[Kevin Holly]

Here are a few questions to start:

Are you adjusting the position of the UIFigure with a startup function or when you create components? Do you use normalized units, which are not supported with App Designer? (if so, I can show you a workaround). Is the app in fullscreen mode?

[John F]

@Kevin Holly

1. No, I don't adjust the position of the UIFigure. I do change the ColumnWidth and RowHeight of the GridLayout in the StartupFcn though.

drawnow
fig_position = app.UIFigure.Position;
fig_width = fig_position(3);
fig_height = fig_position(4);
app.GridLayout.ColumnWidth = {0.54*fig_width, 0.46*fig_width};
app.GridLayout.RowHeight = fig_height;

2. Yes, I use normalized units as much as possible.

3 . Yes, the app is in fullscreen mode.

[Kevin Holly]

After you use normalize units, convert the units back to pixels. This should fix the issue.

[John F]

@Kevin Holly Could you please elaborate on that? Where and why should I convert the units back to pixels? This doesn't feel like it's the source of the problem.

[Kevin Holly]

@John F I had an issue with an app while using Auto-Reflow in the past when I used the unsupported normalized units. Switching back to pixel units resolved my issue. So, I'm not 100% sure that its the issue, just a guess based on my past experience. As for an example, I would add the following line after adjusting the position of your axes (assuming you did this programmatically after converting to normalize units):

app.UIAxes.Units = 'pixels'

Giving it a second look, I noticed you are using R2020b. Have you trying running the app in the lastest release?

[John F]

@Kevin Holly This seems to work if I use drawnow with it. For example:

drawnow
MyPanel = uipanel(app.LeftPanel,"Units","normalized", "Position",[0 0.8 1 0.2]);
drawnow
MyPanel.Units = 'pixels';

However, if I add this to non-problematic panels, it breaks the problematic one, which is strange.

Also, I can't test this in the latest release because R2020b is the newest version my licence gives me access to.