Cannot use pirate ship

[mloballer]

We were unable to play this pirate ship even though there were no workers on it and the player had a worker available and there was a city with space available.

My guess the bug is because he had 3 pirate ships in his city, two of them were empty and one already had a worker on it, he played one, and it worked, then the next turn he tried to play one and got the error message in the screenshot.