@bvk,
We were able to observe the issue but we need to look into it more. We have logged the issue in our database for investigation and for a fix. Once, we will have some news for you, we will update you in this topic.
This issue has been logged as
CELLSNET-46665 - Excel file is corrupted after calling NSeries.Clear() on Surface charts
Good to know that your issue is sorted out by latest version/fix. Feel free to contact us any time if you need further help or have some other issue or queries, we will be happy to assist you soon.