Is your tableau server configured with ssl? If yes, please make sure that in your servertestconfig.yaml file, the hostUri setting entry is correct (i.e. hostUri: https://your_host_server).

If it still doesn't work, please provide more logging by changing "proxyEnabled: true" to true in ServerTestConfig.yaml and open up fiddler to capture traffic between tabjolt and server and share the network capture here.