Removing terrain keeps alphamaps in memory
Hi! I created a 2 layer game (Unity 5.5.4) where a terrain is loaded in an additive scene and removed again later. I am using "Destroy (Terrain.activeTerrain)", "Resources.UnloadUnusedAssets()", "System.GC.Collect()" and "SceneManager.UnloadSceneAsync(scene)". Also set all static references to null.
I used deep-profiling to check which assets were still in memory when this scene was unloaded and it shows a lot of terrain objects, especially the alphamaps of the terrain (in code I am reading info from there but not modifying). When loading a new terrain the memory relicts are accumulating and every terrain costs another 500-1GB of RAM (using >10 splatmaps). Clicking further into the profiler it tells me that the terrain assets were not saved to disk and therefore kept in static memory management. I also searched for ways to update or "save" the terrain as obviously Unity is not doing this automatically when destroying the terrain.
My question is now: how can I completely free RAM from these terrain relicts?