This project is invalid or corrupt and cannot be opened. It may have been created in an earlier version of Storyline.

Hello David and welcome to E-Learning Heroes. 😊

Thank you for sharing what you've experienced with your project files as well.

I took a look at the support case our team worked on with Julie and it looks like there was a network saving factor to consider that may have been causing the issue.

Be sure you're working on your local hard drive (typically your C: drive) when creating, editing, and publishing Storyline courses. Working on a network drive or a USB drive can cause erratic behavior, such as file corruption or an inability to save changes. See this article for more information and tips. 

With your permission, I'd like you to share your project file with our support engineers to investigate what's happening in the latest version. You can share it privately by uploading it here. It will be deleted when troubleshooting is complete.