Just tried to add tracks to a track list with Label Creator (and with the 805 update) and the problem is still there. Using undo still works, however. I usually have to undo 2 times for the text to appear. If you are one of the lucky or talented ones that doesn't have to use undo a lot, it hides under the Edit menu. As I wrote before, you can also use <ctrl>-z to undo.
One hint: When you get to the last track you have added, make sure you have gone to the point where there's a "Click here to enter new Chapter" at the bottom of your list before you hit the OK button. If you don't, your last track will not be in the list Maybe a bit counter-intuitive, but if you think about it sideways, it makes a weird kind of sense
Why the text hides, I dunno. There may be a feature that does some neat thing elsewhere that just happens to cause this glitch for some people, at some times, on some machines. *sigh*
Anyway, hope this helps.