I have created a sample project as showed in the Export article of our documentation, which successfully exports its content in a .xls file in a given directory.
Could you please have a look at it and see how it differs from your approach?
Could you also confirm that .xls set as the file extension for the newly-created file?
Should the issue persist, could you please provide a sample project for me to examine so that I can further assist you with your case?
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Thank you for the sample code and sorry for coming back late as I didn't had a chance to test your code.
The problem with my code was that due to threading the GridView as accessed from non-UI thread, which lead contents of GridView to be in non-accessible state. Then I tried to call the Export function from UI thread and it worked as expected.
Again thank you very much for your quick response, I really appreciate it.