Behaviour of Variables connected to the function Return Node

I have a BP function with an Return Node to which a local Bool variable with default value set to “Fault” is connected. Inside this function there is one dead-end branch, i.e. it is not connected to the Return Node. This branch doesn’t change the value of this Bool variable.

In this scenario my Return Node sometimes returns “True”, sometimes “Fault”. However, if a connect the dead-end branch to the Return Node, I always get the right value, i.e. “Fault”.

Shouldn’t the Return Node bool output automatically default to “Fault” in this scenario?

The problem seemed to be a bug in the engine itself. It has been fixed with the 4.17.2 update.