I found a way to fix the quick notes. Maybe it will work for you. Where it says "Start writing or choose a Template", I clicked on Template. I selected Chore Chart, but then I just went back to the note without applying the template. The hook/checkmark was green! Now I can make quick notes without a problem. I hope this trick can solve your problem, too.
I just upgraded two days ago, but cannot save a new quick note. I restarted, uninstalled, restarted, installed, restarted.The checkbox for saving stayed grayed out and will not let me save. What is the solution?! This is a feature I rely on.
Dee