It sounds like you're trying to import a DNG image file (which is a method some people use to distribute presets, but it's not a preset in itself).
Are you always having trouble with the same file? If so, it's probably best to contact the preset developer, or try deleting the file from Photos app and then download it again from the developer. It appears that the file is corrupted.
The Lightroom Queen - Author of the Lightroom Missing FAQ & Edit Like a Pro books.