Here is the Mathworks support reply to my problem
I am writing in reference to your Technical Support Case #03776780 regarding 'Question concerning app designer'.
I apologize for the delay in getting back to you. I have been discussing regarding the issue with the developers and it appears that the issue is a timing-related bug within the uitable function and is specifically related to the creation of the table.
We have identified three potential workarounds for you that might help in resolving the issue in R2019a.
1. Please try placing the 'drawnow' immediately before setting the Table Data. In other words, your 'startupFcn' could be the following:
app.InstrumentTable = table("RF SOURCE 1", "HP1", 0, 0);
app.UITable.Data = app.InstrumentTable;
After making this change, the issue did not reproduce on my computer in R2019a.
2. If the app is run and the data appears to be missing, this issue can be resolved in real-time by slightly resizing the figure. By resizing the figure, the table will regenerate and it will appear as expected.
3. In R2019a, the UITable function uses a specific infrastructure for data of type 'table'. In order to work around this bug, consider using data of a different data type, e.g. double array or cell array.
Meanwhile, I have also reported the bug to our developers and they are in the process of investigating it further with a potential fix for the next releases of MATLAB. I apologize for the inconvenience caused.
I am closing this case for now. Please write back to me if you have any further questions/ comments regarding the same. I shall be happy to reopen the case and assist you further.
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