Thanks for the post. Based on the error message, it seems like you send the chat message too frequently. Are you getting this error by calling the sendChat interface only once? Where in the call flow do you call this interface?
I do get this error on my first attempt to send chat message (and all subsequent too). I could not find chat in Sample app with custom UI, so I put mentioned method call in the callback of one of the buttons.
Thanks for the reply. The engineering team was able to identify an issue with this interface and we will fix this in the next release. Pardon the inconvenience caused by this.