This issue is also addressed with following patch for 10.6.1:
https://support.esri.com/en/download/7683
対処法
1. Select all rows in the layer's attribute table, click Table Options, and select Export.2. Right-click the feature class within the database in the Catalog tree, and click Export to Shapefile (Single).3. Use the Feature Class to Feature Class tool and export.Refer the steps below for another alternative:
Go to the full extent.
Right-click the layer for the feature class and select Data > Export Data.