The article has information related to using AutoCAD 3D in the Morro Data environment.

File Versions

AutoCAD uses an extensive process for saving files and the process affects how the versioning works in Morro Data. To restore your old versions of the DWG file, open the Manage Versions window for the BAK file of the same name.

The save process causes the versions to be stored in a different file from the DWG file for the project. The reason is that AutoCAD renames the .DWG file to a .TMP file and then creates a new DWG file when the file is saved. The result is that the DWG file does not contain the version history because the DWG file is a newly created file. The TMP file is renamed to the BAK file of the same file name as the DWG so it has the contents of the DWG file. This creates the version chain in the BAK file, and the BAK contains all the version information 

For example, if your project is saved in MorroProject.DWG. When the project is opened, the DWG file is renamed to atpXXXX.tmp. When the file is saved, the file MorroProject.BAK is deleted. The file atpXXXX.tmp file is renamed to MorroProject.BAK and a new file named MorroProject.DMW is created. Therefore, MorroProject.DWG is considered a brand new file.

 More information about the saving process can be found at this article: AutoCAD file save process.