Solution
- Change your preview instance to NO debug object selected, that will automatically make break points work when you put one. Try putting a break point in the even begin play to make sure it hits the event begin play in animation blueprint
- Make sure you haven’t checked in pause anims in the Mesh on the details panel
- For debug purposes, create anim notify from your animation and check if the Notify is firing.
- Also is your gun out of view when you spawn it in the game? that would make it not fire the starting animation.
IMPORTANT : Click on Mesh → Mesh component update → Always tick pose and refresh bones. This will make sure animation will start even if it is out of view.