I know this is a month old thread, but I'm pretty sure you have not resolve this issue.
I did experience the same behavior and so did 5 others techs I know. I don't understand that JCI support told you they did not have a clue about this because they told me a while ago this was a know issue. And the answer they gave me was that the serial tunneling is not supported by JCI, it is offer as is. I can confirm the issue is with the driver but no solution has come. We quit using it, except for few time, and when we do, we cross fingers... sometimes it does work...
So you are not alone.