File extension in APAish filter is broken in latest version

I have just installed Jabref 4.1 64-bit. Previously I was using APAish export filter with *.rtf extension. Now suddenly the files being created don’t have any extension, only DEFAULT is added at the end of the name entered in file dialogue. Every time I have to rename the file with our desired extension to open in Microsoft Word.
Any ideas how the fix it?

This is a known bug in 4.1 and a fix is already in the pipeline.