Reviewing through this behavior I would suggest submitting a case in your secret customer group here in the Jive Community so that the next available support engineer can investigate directly in you instance. When you submit the case, if you can include the following it should help with their investigation:
1. Does this occur with all messages, or does it appear to be limited to a specific piece of text you are sending?
2. Does this appear when sending a message to any user, or is this a specific user?