I have 6 images from Landsat 8 (Green,Red,NIR,SWIR1,SWIR2,NDVI). When I want to layerstack them with "Merge" I always get a result tif which is just black and white, however I can see that all 6 bands contain values. When I save them with "Virtual Raster" and the option "Seperate" i get the result I want. But when I want to save the virtual raster with "Save as" Gtiff I get just a data which contains 0 KB. Anyone has a idea how to fix this?