The ballista reload appears to be bugged: Releasing the right mouse button to reload as the ballista moves to the right side of the screen as the animation finishes, but before the reload sound has stopped playing, will render the ballista useless, as despite moving to the middle of the screen to shoot, it will not shoot any arrows and instead will reload again despite appearing to have an arrow loaded in.
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However, this issue is a Duplicate of MC-137450.
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