I should say that I have successfully tested the export filter separately and it works fine from the export dialog.
I would expect it to work but haven't tried it, have you tried it yet?
I have tried it and its not working, hence my forum post. Export filter doesn't appear to be called at all.
Sorry I won't be able to be much help. But if I were trying it I would try the exact same export that worked with the export filter, except leave the export filter out, then try initiating the export with the export filter set programmatically.
In other words, start with export-settings that are known to work, rather than an empty table.