A negative cycle does not guarantee distance = -∞ to all nodes. If the cycle is not reachable on the path to a target, the distance stays finite.
Example: Node → Node has distance . A negative cycle exists between nodes , , , but they are not on the → path. Distance to is still .
Check which nodes are affected before concluding -∞. Run BFS from each node in a negative cycle to mark all reachable nodes as having distance .