A custom geographic transformation from the 'Create Custom Geographic Transformation' tool is not available in the list of the drop-down menu when the relevant data is present in the data frame.

Additional Information

Workaround

The workflow works in ArcGIS Desktop 10.5 by performing the following:

1. Insert a new data frame.

2. Add any basemap to the data frame.

3. Add a layer to the data frame.

4. Set the data frame coordinate system to that of the added layer.

5. Click the Transformations button, and select Custom1.

Refer to the link for a video of the workflow: https://www.screencast.com/t/rxruxDQ4e.

Steps to Reproduce