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.
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
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-73227 in the post.