I have a Whirlpool # ed5shaxmq00 side-by-side refrigerator (serial # sp4444484; manuf. date 10-03).
By the way its age is about 4-5 years old.
I recently ordered the water filter (in-grill type), part 4396508.
I was told by Whirlpool and filtersfast that this is the correct replacement.

It does not seem to fit.
It goes almost all of the way in, except for 1/4".
It will not turn to lock in place.
I shined a light in the filter hole. I did not see anything to impeed it, broken or otherwise.

It is almost as if it is too short.
Whirlpool indicates that the part changed some time ago.
I do not know why.

ALSO...
I seem to remember having a difficult time of getting the old filter out.
I turned the grill knob a quarter turn, then pulled out.
It resisted at first but eventually came out.