When you started the game, did you generate a brand new map, or did you choose South Nefule County from the list that includes Navezgane and the three pregen maps?
It sounds like you are using a map generated in an older version, which are not compatible with a19.
When you click on 7dtd in your steam games list, a box pops up with the choice to either play or show launcher. Choose show launcher. Go to tools and clean all of your old data. Make sure to choose clean ALL old maps and not just maps not played in the last 30 days.
Once your data is cleaned, go to play game. Choose new random as your map. Give both the seed and the world names you haven't used before. Generating the map can take a bit of time, but is a one time thing per map generated, and you can reuse the same map all through a19, although when a20 drops you should repeat the data cleaning again. That shouldn't be for many months though.