Comment 4 for bug 1966052

In fact, I don't fully get the problem or better say the deployment

You have 1 provider network (prov1) with 2 routers connected to it (r1 and r2), then you have subnet/network 1 connected to r1 and to r2, and then a LB VIP on n1/s1, where you later associate s FIP to it. Something like

    provider
     / \
    r1 r2
    | /
    | /
    | /
   n1/s1
    |
   LB VIP

Both routers have provider as default gateway in that case. And in the case the members are in a subnet connected to r2, you also need to add the loadbalancer there:

    provider
     / \
    r1 r2
    | / \
    | / \
    | / |
   n1/s1 n2/s2
    | |
   LB VIP LB member