[jmciver]

One other thing to consider is that there could be an internal thermostat (or something similar) that opens once the fluid is at normal operating temperature, which would affect the ability to completely fill the system - something similar to the engine coolant system. I don't know this for sure, this is just hunch after going through the fill procedure using ISTA.

FWIW, the first time I filled the transmission, I did not follow the entire procedure (specifically the parts about getting it up to temp to do the last fill), I just essentially did a cold fill as described above. When I opened the system to drain it (I opened the fill plug before the drain plug), I had some oil come out. When I buttoned everything up, oil level was at the edge of the fill hole (similar to when I first opened the fill plug) - car seemed to run fine (with no error messages), but I still wanted to re-do the procedure again. I came back later (after the car was completely cool) to do the complete fill procedure, following all temperature requirements, and was able to get almost an additional quart into the transmission.