Are you really typing "2597C" (with the C)? If so, the upper left swatch is probably 100C (the first numbered swatch in the list, and the one displayed in the upper left of your posted image).
Try typing just "2597".
In the example image that you posted PANTONE Blue 072 C might have been caused by the "7" at the end of your 2597, if you did not type the numbers in fast enough. I just played around with this for a bit, and I had PANTONE Blue 072 C pop up a few times while typing in 2597. If you wait too long in between entering numbers, the find field will simply start looking at your newest key strike. Typing the "7" brings up PANTONE Blue 072 C, as it's the first swatch listed in the Solid Coated library that begins with the number 7.
As Tom mentioned, you only need to type 2597 in to find PANTONE 2597 C in the Solid Coated library, (that's the only color with the value 2597 in that library).
Thanks! I guess I wasn't typing it in fast enough.
I appreciate the help!