This has happened several times. I set a city to build a wonder. It doesn't finish but shows up in the city's building list. It doesn't show the usual 999 next to the clock.  Can't start the item somewhere else. Can't delete the item from the city. The benefits don't accrue so progress is stopped. Most often happens with Manhattan Project, Ironworks, National Intelligence Agency.  I am now at the point that I can't build components for the moon thing. Please advise a solution. Thank you.