Clearing the coordinate system doesn't automatically re-enable the Map Units control

Description

When clearing a data frame’s coordinate system on the Coordinate System tab of the Data Frame Properties dialog box, the Map Units control on the General tab stays disabled.

Cause

The Map Units control should automatically re-enable whenever the data frame's coordinate system is cleared. This is a known issue.

Solution or Workaround

1. Click OK to dismiss the Data Frame Properties dialog box after clearing the coordinate system.
2. Open the Data Frame Properties dialog box again. You will notice that the Map Units list box on the General tab is now enabled.