The Initial Message for Agent Mediators does not appear in Private Chats

There appears to be a bug with the initial message feature.

In my setup, I created a private chat during the experiment stage and added an agent mediator. To instruct the agent mediator on how to interact with the user, I navigated to the agent’s stage-specific prompt for this private chat and opened the advanced settings. Under "Chat Settings," there is an input field for an "Initial Message," with a description stating this message is sent automatically when the conversation begins.

However, when I act as a study participant (by creating a cohort and joining via the cohort link), the initial message does not appear. I have tested this across multiple experiments, cohorts, and agents, and the issue persists. While the agent correctly follows the system prompt after the user sends the first message, it fails to send the initial message.