I have found you need to set the file association on a drive or folder outside of the vault. I usually go to a network drive to do this but I am usually setting the associations back to Solidworks not away from.
Why do you have a need to associate Solidworks files to edrawings?
If you use EPDM, use EPDM admin tool to associate sldprt, sldasm, slddrw extension to edrawings for viewing purpose.
If you right click on a file, View File will open the file in edrawings. View File from hiustory Dialog will opem in edrawings.
When a file is double clicked, it will open in SolidWorks.
Still if you want to open files in edrawings, unitall edrawing, then epdm.
Reinstall EPDM then edrawings and try again.