Unable to use drop down for tooltip widget

The tool tip widget drop down appears to be grayed out and unusable. This feature was available in the 4.18 version of the engine but not longer appears to be usable.

1. Open the editor
2. Create a new widget blueprint
3. Add a text block to the designer tab
4. In the details panel click the down arrow to expand the behavior section

Result: The drop down to select a widget to be used for the tooltip is no longer available and appears grayed out
Expected: The user would be able to select a widget to be used via a drop down menu