The same as mentioned by my colleague above, I wasn't able to see the notes column as I replicated it here on my end.
As a workaround, you can use a custom field for the notes of your items when creating an invoice. Here's how:
Please know with this option, you'll have to manually enter your notes when you create an invoice.
Here's a screenshot for your visual reference.
Please let me know if you have any other questions. I'll be always around to lend you a helping hand.