Hello there, @Maple1.
Thanks for getting back on this thread and providing screenshots about your item notes. Let me step in and help isolate this issue further.
I've tried entering notes using my sample company file on QuickBooks. However, instead of using the Other column on the selected template, I created another field. This is possible by adding a custom field on the item.
Please take a look at my examples below.
This should do the trick. If you've already tried doing this, and still have the same problem, then I'd suggest running the verify and rebuild tool. It might be possible that this is caused by data integrity issues. You can click on this article link for more information: Verify and Rebuild Data in QuickBooks Desktop.
Keep me updated on how it goes. I'll be here to help you further with your item notes if needed.