I just tried the approach. You are absolutely correct - The main IASE localizer does indeed disappear at about 5 DME, as does the IPKN localizer - it vanishes just inside the point on the approach plate where it shows the right hand turn as part of the missed approach procedure. What is more, IPKN appears to be set to a course of about 150 or 330 degrees, not 303 degrees. After (unsuccessfuly) trying to do the missed approach as published, I turned right to due east, and flew until the needle centered, then turned to follow it outbound and I found the airplane tracking parallel, and just to the east of the main IASE localizer.
BC mode in the default G1000 appears NOT to work, and once you select it, regular LOC tracking no longer works either.
IPKN is acting like other offset localizers in MSFS when such offset localizers are linked to a specific runway, in which case the Nav receiver “sees” the localizer as having the runway heading despite how the nav data might actually define it.
Both IASE and IPKN disappear when you get closer to the airport than about 5 miles. Curiously, the IASE localizer CDI needle disappears, but the DME part keeps working
Very strange indeed.
This was with Navigraph active. I will try it again with default data later this evening.