WAN Link Problem

We have 200E model

We have 3 PPPoe links that give us dynamic IP's for browsing.

I created 4 security policies for different subnets  and assign 1 pppoe link as out_interface to each policy.

Initially internet is working fine on all clients with current policies, but when I am changing out_interface on any particular policy, Internet stops working for the subnet present it the policy. 

Did anybody face similar issue in switching of out interface?