Are you really sure it’s not EFS? Can you send a screen shot of such a file in Windows Explorer? Or check properties and ensure that the “Encrypt Contents to Secure Data” is *not* checked? Note that the way EFS-files are distinguished has changed in Windows 10 – now it’s a little small padlock icon overlay, before the text of the file name was in green text.
The situation with Dual Boot you describe is a typical scenario where this will happen if it’s EFS-encrypted in Windows 10 and you then try to access them in Windows 7.