I know you may not want to hear this, but just because the pulley doesn’t look like it’s out of line doesn’t mean that it isn’t.
The belt make shouldn’t matter, as long as the tension is correct (although I also love gatorbacks, Autozone has them too).
Does your pulley have rubber embedded in it? Sometimes that deteriorates (very hard to see) and will throw everything out of balance. You will never be able to really see it.