Might seem like a silly question, but did you wait an extra turn? The bonus isn't added on the turn the consulate is finished, but on the turn after that.

If it has zero food then growth will be capped at 0.

Personally I Raze cities like that when I capture them from the AI. The AI doesn't play by the same city site rules we do, and sites which are viable for an AI are not viable for a player. The last time I razed a city like that, I could instantly see a much better city site I could settle on with a pioneer.

Any city which is that bad (or even close to that bad) is going to cost you unrest in all your other cities for no worthwhile benefit. The only possible benefit I can see from such a city is that if it has Essence you might be able to get some mana from it via Meditation and Produce Mana. Even then I'd question whether it's necessarily worth it for -3% unrest across the rest of your empire.

From memory the Raze button is near the bottom of the screen when you select a city, near the Build/Train buttons etc. You may have to click on "More" to show it though, I can't remember.