In notes preferences , if the box of enable the on my Mac account is checked and you create some note in the folder it will get saved , but not synced with iCloud .
If you open system preferences > Apple ID > iCloud and uncheck the box of notes they will start disappearing from the notes application .
Once again the notes box is checked they will again start downloading / syncing from the iCloud server , it will take hours to sync all of them, high network speed is essential , also depends how much notes data is stored .
If iCloud storage is exceeded from present storage used and you continuously add the notes they won't save , also if notes are continuously added in a folder created in iCloud section see the example screen shot , at certain limits the note will not be saved the data will move up and down ( you can see in bottom end of that folder ) .
