Same thing happened to me on Emirates DXB-PEK last summer. We left DXB at around 4am, landing in PEK at 3pm. It was daylight for most of the flight.
I was at the window, the other two people in my row were pretty much dead from the minute they sat down, yet I was instructed firmly to keep my blind shut. I was very frustrated as, like your daughter, OP, I flew over the Himalayas and very much wanted to see them for the first time. I managed a few peeks, but kept having to close them when the CC walked by. Eventually as the rest of the cabin woke up I was able to open the blind fully again and saw nothing but flat Chinese desert for about 2 hours before landing.
I am flying LHR-SFO in May, I hope this isn't repeated on that flight, I have been TransAtlantic numerous times and never had it happen.