Since the runway has not been commissioned, does it even appear on approach charts/ airport diagrams as a closed runway?
I'm assuming that a text type Notam was in the briefing for the flight, but without a visual presentation of the under-construction runway relative to the operational runway, the crew might not have had a mental picture of what to expect.
Add in a low sun angle and, Voilą, embarassment and potential for serious hazard.