As a workaround, I'm using Privoxy to forward the http traffic to my socks proxy. Just add this line to the privoxy config file:
forward-socks5 / localhost:12345 .
where 12345 is your socks proxy port. Note the dot at the end of the line. Then you can use:
127.0.0.1:8118
in Enpass http proxy (8118 is the default port for Privoxy).
I hope you find this useful