Hello, our store has been experiencing this issue for a few months now, unfortunately.
On our checkout page, there is a box that hasn't changed in over 2 years. It doesn't have a 'submit' button, but we used to receive notes on our orders all the time. I just did a test order on site and confirmed that the note that I submitted did not come through.
There used to be a small icon next to the order numbers that had a note, and again, we do not see this anymore. Has anyone had this issue, and have a quick temporary fix, or ideally a solution?
Thanks for your time!
Try to deactivate the notes, and reactivate again on your theme settings. See if that works.
You can also check this page out from shopify - Order Notes
I was going to say to re-download the template, make a copy of the one you are using, and try to compare the code to see if something is missing. But i don't think we have an option to edit the checkout page.
I hope this helps