Here is the answer people...
Assuming you have upgraded to El Capitan...
and assuming you can't get your notes app on your mac to sync properly with iCloud and your iOS device...
Go into safe mode and open notes there.
You will suddenly see all of you iCloud notes populating where they weren't before.
Let them complete.
Then when you restart normally, your notes should be sync'd properly.
1. Do a Parameter Ram Restart first:
Restart your mac by holding simultaneously these four keys: command+option+p+r.
Let the machine "gong" a couple of times then release the four keys.
2. After the 2nd "gong" hold down the shift key to take her into safe mode.
This start up in safe mode has the added benefit of clearing your cache and you may notice more disk space and / or performance improvements.
You will notice a few extra graphics sweeping vertically on your display, don't be concerned, this is normal.
You should see a red "safe mode" in the upper right corner of your display.
3. Open notes and look for new notes popping up.
4. Restart your machine normally.
5. Open notes and see if all of your iCloud notes are there now.
Test it out; make some new modifications to a note on your iOS device or in iCloud and see if they show up on your notes app on the mac.
You're welcome