I am referring to the altitude in the azimuthal coordinate system, not the height of the sun.
What is altitude in the azimuthal coordinate system? Do you mean elevation angle? Didn't you use an altitude (height above earth) to calculate a predicted angle of elevation for the sun over a flat earth that differed from what was observed?
In this other thread, the FE Opening Post sought to work it the opposite way and claimed that taking an observed angle of the sun, one could calculate its height over a flat earth, for which he derived a value of 5600 miles vice more typical 3000 miles.
Now, if you're talking about something else that I'm missing, and there's no overlap between this topic and that other one, I apologize. I thought you'd just be interested to see that we've been down this road at least once before. And yeah, I agree with your observation.