Yeah, if you get enough hits to meet the threshold set by #, then the invisible (improved) condition is completely resisted by the attacker. If not: GM call based on circumstances in play.
How do we know the condition is completely resisted, as opposed to "can notice but still invisible"?
The GM knows.
The rules don't need to spell out difference between "failed to hit the threshold, and has no idea you're around at all", "failed to hit the threshold, but knows you're here but not where", and "failed to hit the threshold, but still knows right where you are because of environmental cues". GM discretion is the easiest and most reliable way to legislate those differences. In certain cases, like say a guard dog, simply being able to smell you and using scent as its primary sense might mean that being invisible means literally nothing at all to its attack.