You are loosing the top few lines in NTSC where the HP logo is and the clock. But, I guess it is to be expected if HP decided just to drop the ~50 missing lines of video instead of having scaled graphics. Otherwise, your LCD panel is dropping those lines out.
That's exactly how it is presented by the instrument, my LCD does not cut anything, see below. Actually there is enough room for the entire image, I don't know why HP decided to cut their logo in half. If my counting is correct, there's only 238 visible lines in NTSC mode, 263 in total with VSync, BP and FP. The clock is there, take a closer look.
What's left, is to save and recall the color scheme in/from the EEPROM so it starts with the latest scheme instead of a default one. Since I have the code tested, it shouldn't take me more than 30 min to add and test the module, I just need to find the time and the will.
Next step is to make a board, my first board in Kicad, with all the components on the top side (fingers crossed) so it gets assembled by JLCPCB. I don't think two layers is enough but I should be able to place everything on the top layer.