If you have a BP with a function that has no return value, then override that function in a ChildBP, it becomes an event and cannot be used like a normal function
1. Create a BP with 2 Functions, 1 with and 1 without a return value
2. Create a Child blueprint based on #1
3. Override the two functions in the ChildBP
4. Note that overriding the function with return value gives you a normal function
5. Note that overriding the function with no return value gives you an event
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-24635 in the post.