cannot open attachements in notes for Mac

In your original question you wrote :

quicklook shows an empty file icon

Did you tried to open the folder with the help of preview outside notes app , and you also wrote :

I have tried to reset notes by deleting ~/Containers/com.apple.Notes/Container.plist, but this does not help

By deleting Container.plist will delete the Notes Data and could corrupt Notes application .

Now , how to solve it is very tough , run m/c in safe mode and then create a new account see if it works or first take back up of all your data , wipe out the drive and clean install the operating system .

According to this article : Import your notes and files to the Notes app - Apple Support

File formats that you can import

On your iPhone, iPad, or iPod touch, you can import Evernote Export export files (.enex files).

On your Mac, you can import these note formats from anywhere on your computer:

• .txt
• .rtf
• .rtfd
• .html
• .enex (Evernote XML export)

Your notes might look different after you import them. If you have an attachment or feature in your notes that the Notes app doesn't support, it's removed during the import.

Is this question still active? I'm having the exact same problem. I have put a lot of attachments into notes, mostly pdf and jpg files. They appear just fine in notes. I can view them in notes on all my devices through iCloud. But, neither Quick Look Attachment nor Open with Preview work. Quick look just pops up a window with a folder large folder or file icon and Open with Preview does nothing. Selecting the item and pressing space bar does exactly the same thing as double-clicking the item or selecting the option from the right-click menu. Anyone have an idea. I'm running on Sierra. Maybe High Sierra will fix this, but I'm having problems getting the upgrade to run. Thanks for you input.

Just to be clear, there is a big difference between creating an attachment within a note and importing a note.

• Importing a note means bringing in some note-like material created in another application and formulating (converting) it into a note-like form.
• Attaching something to a note means you have created a basic note in the Notes app and are then supplementing that note with some material from another application (e.g., a PDF file).

In your original post you wrote :

It does not seem to have anything to do with iCloud. I have tested it with notes switched off under preferences->iCloud, and the problem remains even for notes that are stored only on the Mac

And you have excluded using I cloud services .

I dragged and dropped a pdf folder into notes using as google account .

Selected the folder ( command + A ) it was highlighted , pressed spacebar it opened with preview .

Here are instructions regarding Notes attachments:

Notes for Mac: Attach photos, links, and more in Notes