I agree, the properties field does have some issues which I believe is simply a display issue. The data contained in the QT file, if extracted, is consistent with our findings.
So in our case even the QT timeline is inaccurate. My final frame is 00:48:00:00 frame 69051. FCP also states final frame is 69051. And if you include chapter markers and compare the time codes between QT and FCP they are off by about 1/1000.
Robert Longwell