Hi,
if the file type simply sais "data" or "file" that usually indicates that the file name extension got removed.
Open a File explorer window. Go to: View>Show>File name extensions.
On the PNG file, check if the file name extension is ".png". If it is not, add it to the end of the file. That should make the file be recognized as a PNG file.
Sincerely,
LightJack