Windows 10 Explorer claims that the folder is empty, but a good search program verifies that the file is there. (file is .odt format).
Windows has been set to show hidden files.
Note: file has never been accessed with a open or available internet connection.
but a good search program verifies that the file is there
What is that “good search program”? Your description and question sounds a bit like your search tool in fact is a forensic recovery tool and shows you a deleted file (I got no other explanation, if File Explorer is set to show hidden files and nonetheless claims the folder to be empty). And if that’s the case, you need to recreate the file first before you could open it using any standard application.
Following on from Opaque’s comment, have you looked in the recycle bin for the file of the sane name. The recycle bin marks files for deletion but doesn’t allow then to be overwritten until the bin is emptied. If you find the file in recycle bin then just right click and select restore
Make a note of the file name. Go to the Recycle Bin find the file of the same name, right-click it and select Restore.