Problem: ArcMap's advanced symbology option for transparency by field works only on polygons
Feature transparency can be adjusted based on an attribute field value. The values represent a percent of transparency (1-100).
This is only available for polygon feature layers symbolized using single symbol and unique values.
Solution or Workaround
Use the Effects toolbar to set layer transparency. This is supported for point, line, and polygon feature layers, as well as for raster layers.