Hi @Zhou, Jie (周杰) ,
I hope you got the resolution from your prior comments.
To help others in the community, let me reiterate the solution here by jotting down the gist of my comment answer above.
Please try to use speak_ssml_async, for testing. If speak_ssml_async is working perfectly, it means all your configuration values are also perfectly provided by you in your code.
The code snippet mentioned in my previous response, is what I tried at my end for testing my custom model and it works as expected.
Hope this helps.
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