Alpha 19 is not compatible with A18 saves or A18 maps. For best results remove all saved data from A18 and avoid using the same exact seed name for your A19 map that you used for A18. If your trader is MIA or you have garbled biomes it means you are playing on an old map.
1) right click on 7 Days to Die in your library
2) select properties
3) click on the betas tab
4) click on the drop down menu
5) scroll down to reveal latest_experimental unstable build and click on it
Clean out A18 data
1) start the game from your library
2) select show game launcher
3) click in the tools tab
4) click on clean game files and check all circles
5) click clean
If you are certain you have cleaned out all old data and are still having issues please go HERE to report bugs for the PC version only.