I am so angry right now. I just spent time programming drums during my brothers Guitar Solo section in SPrem. 20 minutes with fine tuning and some of the most creative work I've done in a long time.
 
BAM! Sonar crashes.
 
That's ok! I'll revert to my auto saves - since I have it set to save every 2 minutes/every 10 changes AND keep 10 versions.
 
BAM! NO files to revert to. Not ONE. File/Restore window is empty.
 
Not a happy camper.

The "Revert"-menu is only for versioning.
Auto Save works, also Versioning.
We keep 999 Versions, and have hundreds of "autosave*.cwp" and "*.~2015*" files in the projectfolder.
 

Yes, look in the project folder for the auto-save copy. The auto-save copy is not presented in the revert dialog.

Guys trust me. There was one auto save and no versions.
 
Once I restarted Cakewalk it began version-ing again.
 
I'm not a fan of software I have to restart or worse reboot in order to ensure it works.

The title is misleading, auto save appears to work, versioning did not. I cannot say I have ever had versioning fail. I do power down my PC every night and cold start every morning. I do manually save in addition to autosave and versioning, just in case.
 
Edit: Might want to take a look at the Windows Event Viewer for errors.