When RS fails to save through the application or a file is lost, you can try to find a copy of the file that is located in the temp location. This article explains how to fine the Temp location.
After you retrieve this version of the file, open it in Photoshop to check at what state of progress this file has been saved at. Close the instance of RS that is open and re-launch the retrieved file in RS. Remember that saving to the desktop is always advised as the safest place to save files rather than server or external locations. Open Terminal  (can use search bar search “terminal” to open it or go to Applications)
Type "echo $TMPDIR”
Hit enter
Terminal Will give you a path in the next line
Copy that path and go to “go>go to folder”
Paste in path and hit enter
It will take you to that location on the computer. Search there to see if you see the file and copy it to the desktop.
The path looks something like this:
/var/folders/3_/4t3r2bx50cj72p55nzzkhg3w0000gn/T/