When I save my park and go back to play it, all of my work is gone and there is no park entrance. I have to load a new game and start over. I have been unable to save progress on all of my park creations.
Are you loading your saved parks under the "My Parks" icon in the top left corner of the welcome screen? There you will be able to find all your saved parks.
If you are certain that you have saved and loaded your park correctly, you should consider preparing screenshots or a video of this occuring, and file an issue in the bug reports forum.
