As I further investigate this minor - but strange issue, I am realizing that the "one-letter" keyboard shortcuts are only failing when either shortcutting-to or shortcutting-from the text tool (T).
I have reset my Type Tool shortcut and tried reassigning it and the problem persists. It seems the only way to activate the type tool is to click on it...it's like InDesign cannot load the type tool and allof its settings when prompted from a shortcut key.