The issue is likely due to the size of the app, particularly the number of ‘GridLayout’ components. If App Designer's loading process takes a long time, App Designer can become disconnected from MATLAB, causing issues with saving. To help resolve the issue, try the following steps:
1. Upgrade to the latest release of MATLAB. App Designer's performance has improved significantly in recent versions.
2. Consider reducing the number of 'GridLayout' components. You might use the 'AutoResizeChildren' property on containers to manage resizing more efficiently.
3. Extract some parts of the app into a separate app. Use the main app to create the second app and reparent the components from the second app into the main app. For example:
% Create the App2 instance
a2 = app2;
% Change the parent of the Panel in that App to our own figure
a2.Panel.Parent = app.UIFigure;
4. For any long callbacks, take the code into M-files and call those M-files from the callback. Also extract helper methods into separate M-files.
This should help resolve the saving issue.
