A layer in your map is symbolized with the size renderer and uses an arrow marker symbol. Because of differences in the display engine, there may be some discrepancies in the size of the arrows when viewed in a map service or a basemap layer.
Solutions
- Switch to a different type of marker symbol, such as a character marker. Other types of markers do not exhibit these differences.
- Change the symbology properties of the layer to not use the size renderer.
More information
This warning message is simply telling you that the size of this symbol may be different in a basemap layer or a map service. This is because the drawing engine used by basemap layers and map services scales the size of this type of symbol differently.