I just upgraded this plug-in to the latest version (I was using an older version which stopped working in the last few weeks).
Now the file extension it is generating is a “PNG”. I am on a mac with firefox.
It does it on your demo page too. Here are screen shots of both my app, and yours, with the PNG extension.
(I tried adding .csv to my file name, it just adds on the .PNG on top of it all)
Hi @soundguru,
Thank you for getting in touch!
I have replicated the issue on our end. While I was able to change the file type to .csv without any difficulties, I noticed that the default type is set to PNG. We are currently looking into this matter and will explore possible solutions.
I’ll keep you informed once we have any news. If you have any further questions, please let me know.
Best regards,
Gulce
Hello @soundguru,
Thanks for your patience. 
We’ve updated the plugin and fixed the issue. Please upgrade your plugin to the latest version and give it a try.
If we can help you with anything else, please let us know.
Best regards,
Gulce
Thanks, I will check it out