I had exactly the same issue: Three out of four seats blocked, one free on expertflyer. So, I called and also got the answer that no window seats are available. Thus, I said, I would try my luck at the airport then and they should not assign me a seat. But the operator must have entered a seat preference at that time to my booking because shortly after my call both of the non-Swiss flights on that itinerary showed up with confirmed window seats on checkmytrip (and I hadn't called any of those airlines or requested any seats there). In line with my request, there is no seat assignment for the Swiss F flight on checkmytrip. However, when checking back on expertflyer five minutes after my call seat 1A had changed from being blocked to being occupied. So, I am optimistic that I will get a window seat assigned at the airport.