1. Create a C++ project from ThirdPersonTemplate.
2. Declare a Dynamic Delegate with ReturnValue in ThirdPersonCharacter.h, like DECLARE_DYNAMIC_DELEGATE_RetVal(bool, FTestDynamicDelegateWithRetVal)
3. Declare the Delegate UProperty with BlueprintReadWrite Specifier named "TestDynamicDelegateWithRetVal" in AThirdPersonCharacter.
4. Open ThirdPersonCharacter BP and Right-Click in EventGraph, select "Set TestDynamicDelegateWithRetVal".
5. Drag off of the Event input pin and release to show the context menu.
6. Select Event Dispatchers/Add Event in the context menu.
7. Create a Function with a Return Value of the same type of the Delegate.
8. The "Create Event" node can't select the Function.
I upload a project to reproduce.
There's no existing public thread on this issue, so head over to AnswerHub just mention UE-68763 in the post.