First, go into the Full Grade Center.
In the Final Course Grade column, click the gray chevron in the top cell and choose Edit Column Information.
Next, take a look at the Primary Display. In this example, it's set to Letter--which is an entirely logical thing to choose!
Here's the trick, though: In order to display an accurate letter grade, the Primary Display must be set to Text instead of Letter. (In Blackboard, Letter has a specific use, but it's not one we use at TCC.)
Once it's changed to Text, it should display correctly.