Hello,
This Microsoft official article could be a helpful resource for your issue: assign a user directly to a session host.
If the article doesn’t resolve your concern, we encourage you to post your question on Microsoft Q&A. Microsoft Q&A has dedicated Azure engineers who can offer expert and timely support. Simply click the "Ask a Question" button in the top right corner, include relevant details, and select appropriate product tags to ensure your query reaches the right experts.
I hope this information helps.
Best regards,
Karlie Weng