Why did they ABANDON the giant obelisk in Aswan mid-cut?

Aswan, the granite quarries on the east bank. There's an obelisk still lying in the bedrock, never finished, never lifted. If they'd raised it, it would've been the biggest ever made, around 42 metres, nearly 1100 tons. Attributed to Hatshepsut, so 1500 BC-ish. You can see exactly how they were work……