@madbrain Sounds really strange that a name change would have such an effect...
And when adding the third interface, all you do is put that into the existing group, also set as Tier 1 like the others? And that breaks the load balancing completely?
And what about policy rules? Do you have a rule both for the loadbalancer and the failover gateway as per that guide?
If so, you need to make sure the balancer rule is above the failover, since rules are handled from the top.
BTW, how do you go about changing the names of the gateways? Did you edit the config file or do you copy the gateway, give it a new name and then delete the old one?
Changing name on a gateway can't be done without affecting other things, like the FW rules for example.