Terrain follow not engaging

Having trouble engaging terrain following in missions. Terrain following is enabled in params, all waypoints are set to terrain, the altitude elevation graph shows the mission adjusting for elevation change, the map is pre-cached, and when flying the mission the waypoints are accurately followed except for the change in elevation, elevation is maintained relative to home point the entire time. Looking over the terrain following guide manual I cannot find any other ways to address the issue that I have not already.

Any help is appreciated