I found something while playing a game and winning the stable building quest and getting the +1 food bonus. I noticed that I do get the bonus on new stables while in the same session, but building any more in a new session doesn't offer the bonus.

It might also be of notice to see if other quest bonuses are affected this way. Also is there a means of adding text if a bonus applies to one city's or all cities buildings?

Update: Found that the issue is that the bonus only applies on the same continent as capital. This could be something to discuss weather to change it to all cities.