A picture of the forward components as well as the windlass would help.
I wonder if there is something wrong with the roller mechanism forward. You either have a roller assembly or a pulpit with a roller of some sort where the line makes the turn down towards the water. Have you checked that area? Perhaps the roller or supporting metal assemble has issues. For example if the line slid off the roller and got caught between the side of the roller and the bracket, it could rub on the roller axle which could be a threaded bolt. That could wear out the line when at anchor in a hurry.
I wonder if there is something wrong with the roller mechanism forward. You either have a roller assembly or a pulpit with a roller of some sort where the line makes the turn down towards the water. Have you checked that area? Perhaps the roller or supporting metal assemble has issues. For example if the line slid off the roller and got caught between the side of the roller and the bracket, it could rub on the roller axle which could be a threaded bolt. That could wear out the line when at anchor in a hurry.