D,
I see nothing wrong with your diagram..
I assume it works when the breaker and load do not go through the relay.. Yes???
If so, then the problem is that the relay is not closing.
I see you have an 5P IntelliCenter.. Normally this means you have 5 relays.. The first one is the pump/filter relay then Aux 1, 2, 3, 4 and the next is 5
What Aux relay are you using?? Your diagram shows Aux 8, but you don't have access to 6, 7 and 8..
How are you trying to turn on the Aux relay? Button, App or ??
Thanks,
Jim R.