I think that only the relatively new lenses are chipped for serial number, i.e. lenses designed after Canon decided to add that feature to the 1D X. A CPN article states, " If the serial number of your lens isn't detected it's possible to register a serial number for a lens within the camera menu."
My 70-200 II serial number was never detected, my 40mm f/2.8 pancake serial number is shown, even as the AFMA values for it are zeroed out.
So your setting for the 40mm is being lost, eventhough it's being recognized by the camera.. Euff.. will try the 8-15 one more time.
The camera isn't recognizing the lens has having been previously registered with an AFMA value. It still reads the model name and serial number off the lens just fine. Like John said, lenses released before 2011 (even if they were purchased after then) do not have the serial number on the chip. For example, I have a 70-200mm IS II that was purchased in mid-2011 that does not show a serial number on the 1D X (and on the 5DIII).
I tried the 8-15.. settings are saved.. tried changing the lens.. (the 50 1.4) is being recognized as "01" meaning it's thinking that it's another 50 1.4.. turned off the camera, attached the 8-15.. settings are retained!!
I can't make any sense from this..
The camera numbers lenses sequentially, regardless of the model. So you have the 8-15mm registered in slot [00]. When you mounted the 50mm 1.4, that lens was set to be registered in slot [01]. If you didn't register a value and mounted another lens, it would still show [01]. If you did register a value for the 50mm 1.4, then mounting a third lens would show [02].
Yes.. I mistakenly thought "each" lens started it's own numbering... I just checked the settings for the "orientation linked AF point" and it was "Same for both vert/horiz".
so that's why the settings for the 8-15 were being saved.. will try to change it to "select separate AF points" and try the 8-15 again.