Ok, I am totally new to Jabref but I am not new to programming etc. That said, I am trying to create a export filter to format some a .bib into a .csv. I went to the jabref help and to https://cynthiadangelo.com/2012/10/22/exporting-mendeley-tags/ in order to figure it out. I created a new .layout etc and Menu Options – Manage custom exports – Add new But everytime I export I get exactly the same output I do see in the drop down menu for export there are two .csv outputs listed but neither have the name I gave it when I “Add new” I have tried all kinds of things, now I am beating my head against the wall. I am missing something simple?
Hi,
you did all right 
In the current 4.2 there’s a bug with the selection of the custom export filter.
The good news, there’s already a fixed version.
You need this special development version.
https://builds.jabref.org/fixCustomExportFileType/
For reference: https://github.com/JabRef/jabref/pull/4015
The fix is not yet merged into master, but we are working on it.
Regards
Christoph