Hi, this is most likely to do with the Terrain Level. Some items may require you to raise the height. For example. The creator might have made a coaster station that sits below ground level as it was built into a dip or hole. That cannot be placed underground on your map. Try turning off Terrain Collision in settings. Watch out though, the height of the rides may still need to be raised. As a test. Get 'Dragon Skies' from my Workshop. I only suggest this as I know it's fine on flat terrain.