It's the same issue as last time. A JOIN related change in v28.0 is putting one of the nodes in your cluster in a state where the write queue is stuck on just that node due to a deadlock. We're very closer to releasing a patch for this issue. And then this should no longer be an issue. In the meantime, you could query the GET /collections endpoints on each of the individual hostnames periodically and look at the

num_documents

field in the response, to verify the state of the nodes.