QGIS not reading elevations from GeoTIFF created by ACADCIVIL?

I've generated a raster DEM in ACADCIVIL in TIFF format: name.tif & name.tif.aux.xml. ArcGIS reads the data correctly but QGIS sets the whole data to the same value = minimum height Looks that QGIS 3.4 doesn't support this format. Same happens on 2.18

gdalinfo output:

Driver: GTiff/GeoTIFF
Files: Surface1.tif
       Surface1.tif.aux.xml
Size is 405, 528
Coordinate System is:
LOCAL_CS["POSGAR_07_F5",
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]

Origin = (5512262.832999999634922,6109047.309000000357628)
Pixel Size = (1.000000000000000,-1.000000000000000)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_SOFTWARE=Autodesk Civil3D 2008
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  ( 5512262.833, 6109047.309) 
Lower Left  ( 5512262.833, 6108519.309) 

Upper Right ( 5512667.833, 6109047.309) 
Lower Right ( 5512667.833, 6108519.309) 
Center      ( 5512465.333, 6108783.309) 
Band 1 Block=405x100 Type=Float32, ColorInterp=Gray
  Min=38.088 Max=39.473 
  Minimum=38.088, Maximum=39.473, Mean=38.565, StdDev=0.301
  NoData Value=3.4028234663852886e+38
  Offset: 38.082,   Scale:0
  Metadata:
    STATISTICS_COVARIANCES=9.08270199017587E-02

    STATISTICS_MAXIMUM=39.473079681396
    STATISTICS_MEAN=38.564526756118
    STATISTICS_MINIMUM=38.088008880615
    STATISTICS_STDDEV=0.30137388124225
    STATISTICS_VALID_PERCENT=52.86

I've changed scale to 1 --> same result File Properties --> Info Band

Number Band No-Data Min Max 1 Band 1 3.40282e+38 n/a n/a

Answer

Everything looks fine in the GeoTIFF file info, except the Offset and Scale values.

Offset is a fixed value added to all the cell values, it should be 0.
Scale is a multiplying factor for all cell values, it should be 1.

Therefore, you need to make a translate:

gdal_translate -a_offset 0 -a_scale 1 Surface1.tif somefilename.tif

QGIS can now correctly represent the generated file.