We are developing a Messenger chatbot with Node.js and API.ai. The bot hasn't been published yet and only users that are admins for both the app and the page can talk to it. We are currently two admins. When one of us talks to the bot through Messenger, she gets this error message: "This message failed to send. Click to send again." The server does receive the message and responds accordingly though, so the message doesn't seem to fail in reality.
When I talk to the bot, I don't get the error message and the conversation works as expected.
Any idea what could cause something like this?