Photoshop files completely disappearing

I teach Adobe Photoshop in high school, and for the last few days, my students' files have been completely disappearing from the desktop. All of their work from the day or days before are simply gone. They can see the image of the work they created the day before in the home screen of the Photoshp interface, and it says the name in "recent files", but their files are gone and those won't open that they are seeing listed as there. They have to start completely over, and they are worried that their new work will be gone as well when they come back to class tomorrow. It started happening when I got a notification this past week that cloud synching will end. Did that do something to create this issue? I have been working in Adobe Photoshop since 1995, and have never ever had an issue like this. Please advise where their files are going. They are saving them to their local destop in a folder on their MAC computers.

Thank you.