I have the same Drzewiecki Design Seattle Landmarks installed, which I purchased from the Marketplace. Tonight I made two takeoffs and landings on runway 16L, and had no CTD problems . I was flying the Cessna 172 G1000 (with the G1000 mod). On the second flight I set up an ILS approach to RWY16L (110.3) and initially it captured the localizer and glideslope but I had to turn off the autopilot and land manually when the altitude was about 500 ft. because it deviated from the runway. Hope this is helpful.