Same thing happened to me.
I worked for about an hour on my project yesterday, saving regularly after reading here about the issues, opened the project this morning and none of yesterday’s work had saved. I was going back and forth between normal view and Outline view. I haven’t had any problems with any previous beta versions.
I am saving the projects to the My Documents folder, this is a project that was started on the beta of Scrivener two versions ago.
The work that I did this morning, using just one type of view, has saved properly.