I checked the map in P3D and the frequencies are correct. I'ved checked the AFCAD in use and that is also correct, KORD_ADEX_FSDT.bgl I suspect it is a scenery issue but cannot figure what the problem is. ILS 28C is set in the FMC, NOT RNAV.
That's NOT a scenery issue, which you can easily confirm if you open the KORD V2 AFCAD with ADE, it will show 28C ILS is correctly set with its proper frequency of 108.95, and it's proper ID IVZE
Before saying it's a scenery problem, it's always best to check with a default airplane first.
The PMDG airplanes, as far as I know, do not "tune" the ILS from the scenery, like default airplanes do, they rely on their own Navdata so, if something doesn't work, especially on an airport like this that most of its runways updated, it's usually a problem of not having updated the airplane own Navdata.
As you can see in the attached screenshot, 28C IVZE ILS works just fine with a default 737, showing the scenery is not a problem.