I received a ps file and the layers are still intact, when I pull it into Illustrator it flattens to one layer even though I have the convert layers to objects selected. This is not the first time this has happened to me, some files I get work and then other times this is what happens. Is there an option somewhere in ps that I need to make sure is set to get it to open in Illustrator with the layers intact? I'm using mac os 10.7.5
I wonder if there is a right pointing triangle before the Illustrator layer name. Forgive me if it's something you already know,but clicking on it may reveal the nested objects. It's the first thing I check if I see just "Layer 1" in the Layers panel.
Ok, then the only other thing I can think of is the Link option was selected when you used the Place command to bring it in as an editable file.
Perhaps this resource might help you chase the problem down, or at least give you an workable alternative.
If this gives nothing,I can only recommend the Illustrator forums. Good luck.