Decimal values set on SQL Server REAL data type data in ArcMap does not persist when published to Portal for ArcGIS.

Solución alternativa

Use the CAST function in the Query Layer SQL statement, and change the REAL data type field to Float data type.

For example: 

1. Select Scada_Tag, DateTime, CAST (Most_Recent as float) as Most_Recent from scadadata.dbo.Scada_Most_Recent_vw
2. Then in ArcMap > Scada_Most_Recent_vw set the decimal values on the Most_Recent (Right-click the field > Properties > Numeric > (Number of decimals places: 2).
3. Publish the map service to Portal for ArcGIS.

Pasos para reproducir