I found this information also in my data. As 18 means the distance in NM, this is also true for other ILS like IBE.
The funny thing is, that all ILS are working properly, but not the ICF. I tried in the mean time with the C-172, with the G1000, GNS 430 and GNS 530. All the same: all ILS so far OK, but not the ICF. I have no answer and no idea to solve this problem.
Sorry for this inconvinience. I found the cause (at the time the location of the cause) for that problem:
I have two instances of X-Plane. Finally I made a testflight with an other instance and the problem was gone.