Neither of them needs to be wrong. My reading doesn't disregard any rules, merely accepts that the rules do not cover every situation and that the GM uses at least a modicum of common sense. That hiding makes your location unknown, doesn't in any way require that other things couldn't make your location unknown too.The rules aren't perfect. They contain errors, hence why they've put forward errata. Clearly they haven't captured all of it. The questions then become: Is the entire section on hiding in combination with certain rules in the combat chapter wrong? Or is it just second paragraph of the ranger's feral sense ability that is wrong? The answer is obvious in my view, particularly as the designers have endorsed the entire section on hiding and how that works quite clearly as it relates to invisibility.
I makes sense well enough. The ranger can 'see' through invisibility but not through walls or other obstacles.I think most people not trying to win an argument about this specific topic and who are just trying to examine feral senses on its own reach will also tend to reach the conclusion that the ranger ability is badly written and can be disregarded. Feel free to google such discussions to see for yourself. The consensus is clear that the second paragraph of feral senses doesn't make any, well, sense.