Difficult to say without seeing the data, but probably you need to create another calculated field to show both TN and Tennessee as "Tennessee".
Then put that new field in label.
I don't think Tableau is throwing out the data. Once you have done Edit Locations and specified what state to match it to, they are being placed in the viz. I think what you are seeing is that Tableau doesn't aggregate all of the messy names into the single entity. So TN and Tennessee are both being mapped as Tennessee and the two marks are being stacked on top of each other. If you convert it to a point map and then do a selection around it, you'll see that there are two marks being selected. You could also group these items and then place the group on level of detail and that should work for you.