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Have you tried setting a host instead of ""?
If you want to run JupyterHub under a prefix you should set
hub:
baseUrl: /jupyter
in your config instead. This will configure JupyterHub to run under that prefix, and the Helm Chart will automatically add that to the ingress configuration, you shouldn’t need to specify pathSuffix. I thought this was in the Z2JH docs but I can’t find it 