have you tried to simply re-apply the proposal? I have been facing this a couple of times, especially if the network configuration of the node is supposed to change significantly after a proposal deployment.
If re-applying doesn't help it probably is a faulty network config in the network.json. If you have any access to the control node, try to find out what crowbar has configured and how it should have been configured according to your design, that should lead to the cause.