When I was booking an Aug trip the seat map for one flight was also missing and I was not able to get any seat. The itinerary was tickted without any problem, though. I called and was told that the equipment was undertermined. ~10 days later the seat map appeared.

So I guess a week is not exceptionally long for OP's situation. I've no idea what will happen to your original seat assignment. Possibly you still have it, or you can get a similarly good one.