1. Does the file really exist? Is it in the correct extension? (xyz.page.template)
2. What tool did you use to move the file? If you used FTP, you must synchronize your site's folders afterward.
3. If the above does not work, back up your templates, delete the Templates folder, re-create that folder and upload the files via File Manager.
I'm not sure what your problem is, but I can confirm that Page Templates work fine in DNN 4.8.2
HTH,
Duc