Signal K Error Processing RMB message

Hi the moderator on the Signal K to "Raymarine Seatalk NG" thread on OpenMarine Forum suggested I contact you. I find that when Signal K receives an RMB message from OpenCPN via a UDP connection it throws an error, which I don't fully understand. It seems to be related to a Null value for latitude even though there is no such value in the RMB message. This error is preventing the Signalk-to-nmea2000 pluging providing navigation data required by autopilots. Any advice or fix you can offer would be greatly appreciated.