基于Google Actions的智能家居Java应用执行请求无响应求助

I've built a simple Java smart home app based on Google's smart home sample code, completed the relevant Codelabs, and implemented responses for the three core intents: action.devices.SYNC, action.devices.QUERY, and action.devices.EXECUTE. All responses have passed validation via Google's official validator and standard JSON validators. I've also set up a basic OAuth authorization flow and created a Google Smart Home Actions project.

Current Setup & Observations #

• The test app shows up in the "Add devices" menu. After selecting and connecting, Google completes OAuth verification successfully (logs from Nginx and my app both confirm this).
• Google sends an action.devices.SYNC request to my server, and I return the following response:

{ 
  "requestId":"14182994871341693427", 
  "payload":{ 
    "agentUserId":"rysiek", 
    "devices":[{ 
      "id":"dev1", 
      "type":"action.devices.types.LIGHT", 
      "traits":["action.devices.traits.OnOff"], 
      "name":{ 
        "name":"główne" 
      }, 
      "willReportState":false, 
      "roomHint":"pokój dzienny" 
    }] 
  } 
}

• When I set willReportState to true, Google Assistant prompts me to assign a room to the device. After finishing this step, all functionality breaks:
  • When I use Polish commands like 「Włącz światło główne」 or 「Włącz światło główne w pokoju dziennym」, Google only returns web search results instead of sending an action.devices.EXECUTE request to my server (no related entries appear in Nginx logs).

Additional Context #

• Google Assistant launched in Poland on January 16, 2019. When I say the Polish command 「Ok Google, synchronizuj moje urządzenia」, I get an English response: "Sorry, I didn't get any response." However, my server does receive and respond to the SYNC request correctly.
• My Google Chromecast is connected to Google Assistant properly. The Polish command 「Włącz telewizor」 works perfectly to turn on the TV.

I'm looking for troubleshooting steps or solutions to resolve this issue.

内容的提问来源于stack exchange，提问作者RyszardTrojnacki