Simply "Un-Hiding" solved the "Folder is Empty" error for me.
Shortly after I had upgraded from an older version of Wise Folder Hider to Version 4.11.143, everything was working fine, then one day I opened the program as normal, but when I tried to view the files, it said "Folder is empty."
I tried all of the various methods described in the help files, but Wise Data Recovery showed no files in the [[[[[[[[[[... folder, then quit showing the [[[[[[[[[[[[... folder at all.
Finally, after rebooting, reinstalling, pulling out significant amounts of hair, sending desperate notes to the WiseCleaner staff, I happened upon a simple solution.
In the main WFH screen, rather than selecting "Make Visible" I selected "Un-hide."
Boom! There were all of my files.
I went through and un-hid each folder, and all of the files appeared and work fine.
I will back up the files and try hiding them again, and see if the problem returns.
I used WFH for several years with no problems. I have no idea what might have happened to make them suddenly inaccessible, but I'm very relieved to have recovered my files.
I hope this helps others.