Issues with a Terrain's Level of Detail
Earth Files
There is an occasional issue with some earth files that causes the wrong LOD to show up on the terrain. If this occurs, delete the cache in ./appData/cache and add the following to the terrain section of your earth file: progressive="true"
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MetaFlight Terrains
Indirect rendering and MetaFlight terrains have problems with holes appearing as LODs are paging in. The workaround is to disable indirect rendering for MetaFlight terrains.