I was under the impression all resources get shared between cities in regions, hence the ability to specialize certain cities for particular resources. I am running in to a problem with Food and Water. I am producing plenty to support my needs and stores fill up rapidly to max capacity (8 mil food and 10 mil water) when I am in the city where I have my food and water production.

However, if I switch to my city that has my banks and research facilities, which also happens to be my city with the highest population (30,000 at this point), food and water stores take a dive--eventually to zero if I don't leave the city. If I leave that city and move to another city it balances, but only grows rapidly again if I move to the city where the food and water is being produced.

Is this normal? Is there a bug?