Steps to replicate:
- Create or use any blueprint
- Create a timeline in the Event Graph
- Leave the length at it’s default value (5 seconds).
- Make any track that basically go’s from 0 to 1 second.
- Leave “Use Last Keyframe” unchecked.
- Compile the blueprint.
Now when you start your game/run the timeline, whatever you want to happened in 1 second will happen, but then the timeline continues to loop all the way up to 5 seconds because that is what the length value is set to, and Use Last Keyframe is unchecked (this isn’t the bug).
Now if you go back to the timeline and check Use Last Keyframe and start the timeline again, it will once again perform the stuff for 1 second, but it will continue to run till 5 seconds as if Use Last Keyframe is unchecked.
The reason for this is because whenever you edit a timeline, it doesn’t ask for you to compile your blueprint.
So now, add an Event Tick node just for the sake of it asking to compile. Once you compile, the timeline will run the correct way.