Mast is unrepairable?

So I know masts can be destroyed and repaired now for a while, but something strange happened in a fight perhaps someone more experienced could explain. they broke our mast, we fully repaired it with 3 planks, they did not hit our mast again, they his the boat hull and the mast went down instantly. this repeated 5x. we repair the mast, try to leave but any boat damage what so ever (never to the mast itself) mast would go back down instantly. at one point id hoist the mast then go down to repair it and it literally would not let me repair it unhoisted the instant I let go of the rope. So what's the deal? what should we do in a fight with a broken mast that is impossible to repeair / keep up. Is that by design or a bug, is there a known exploit with masts? does losing a mast just mean certain death now? Very curious.