She can smell them, unless she has something physically wrong with her scent detectors in her nose. She just wont acknowledge their scent presence... hmm.
Never had that problem before.
I would try this:
1. blind fold the dog, with a towel or a sock.
2. place her food inher bowel, but not in the usual spot.(if shes outside dog, put it in the yard; inside, put it in a different room.)
3. Next get her within 10' or so of the food (make sure she is hungry)
4. Let her sniff around to find her bowel.
5. The reward is supper, and take the apparatus off...

I would also do this with a fav. toy. Blind fold, sniff, play with toy as reward.

Progress into bird wings during yard work, let her find the scent with her nose, then point. Blind folded if need be.

Make her "work" for food, toys, or during yard work. I dont think her sniffer is broken, but I think she is getting bored and inversely lazy. Hence the easier sight points. Keep changing up your training tactics, never do a same routine, she will start getting bored of the same old games.

It could take a week or more, and I dont know if it will even work, but I would try it... Good luck.