What reasons are there that a sales order item, would be backordered, when there is quantity available? Do not commit is not selected, and inventory location has available turned on..

Go to the reallocate items page and see if anything looks off.

It’s really odd. On the item itself, it says 16 available. no backorders. It’s like I’m working with two different products

Usually weird stuff happens like this when special orders get modified, or inventory is already committed and gets adjusted out, etc.

Refresh the line in question by re-selecting it in the line... or close that line & add the same item back to the order.

Check if you have a line field called “inventory Location”