I just had the final (3rd) coat of satin polyurethane but on our 5" plank Birch floor (floor has dark stain). They appeared to put it on rather thick, using a paint roller. Thirty hours later the floor is dry but completely covered with 1/2" milky spots; it looks like someone wet the entire floor and let the beaded water dry (this of course did not happen). Has anyone seen this before? Any idea why this happened?

Also, there are very-noticeable swirls of scratches beneath the poly, about 1.5 feet wide. Is this normal or should they have used smoother sandpaper?

Any help would be appreciated.

You should call the finisher back and have him/her examine the job and answer your questions. Swirl in the finish is a common problem all us finishers struggle with. I can't comment on white spots; that could be contamination. I don't know. You may need the floor buffed again and another coat of finish applied. The finisher that did the work will best be able to give you the correct answers I would think.

I'm wondering if it is a waterbased, that has lost adhesion of a coat.