I wasn’t the OP but I was searching for the same thing as them, and after testing it, that won’t work in a blueprint task specifically because “enable input” only works on actors, not behavior tree tasks.
Your recommendation to use an interface did solve the issue for me though! Here’s how I got the result I wanted using an interface instead of directly-implementing input in the task: First I set up an interface with a function called “Dialog Response” with just a generic “object” as input. I assigned the interface to both the behavior tree class and the first person character class where I have all my input handling.
Then in the behavior tree class I got the player character and called the Dialog Response (message) function I just created in the interface, using a reference to self as the “current task.” For simplicity, I implemented the same event on the graph below, and hooked it up to the action I want the enhanced input to trigger.
Next in the first person character blueprint, I implemented the interface event and promoted the “current task” object input to a variable. Then I added an event for the enhanced input key I want to use, and went off the “started” pin so each press would only trigger one task. I validated that the variable wasn’t empty and called the interface event back at the dialog task, clearing the variable afterwards.