Download Altitude Data
When selecting all altitude data options (925, 850, 700, 600, 500, 400, 300 and 200 mb), the GRIB file downloaded contain the altitude data.
When using only the 'All' option, the GRIB file downloaded does not contain data for the altitude layers, only for surface.
Selecting Skew-T only, it also works ok, downloading all the altitude data.
So, the problem seems to be in 'All' option.
Tested for GFS model.