I will confirm EFW2.2 Stable Release can use fail-over.
Because, now I use 1PC with 3 NIC (1NIC for Green and 2NIC for RED) and config it for fail-over.
When I try to down WAN1 and wait about not over 5 minute. Routing is switch to WAN2 automatically.
And when WAN1 is up, routing is switch to WAN1 again (automatically).
If you can't use fail-over. Checking your config again.
see the example picture and try to config again (this picture show config of WAN2 for backup)
You must config this in WAN1 too.Goodluck!
Example Picture