Hello,
I'm in the exact same problem, we are 3 with 4 cities around the great works, and I started yesterday the Airport, I gave 1M$, we waited for the works to begin, and then, 10 min after, the games tell me that something happened when the great work were launched, and I had my money back.
But now, I see that the Arcology is launched, but all my friends see the Airport on place!
I start a new city next to mine, just waited 2 minutes, and I saw the great Airport is under construction.
No idea what happened, I'm stuck because I'm the city full of petrol who supposed to supplie the construction of the airport, but I can't send it!
(Sorry for my English, from France)