[App_rpt-users] RTCM -> "Warning: GPS Data time period elapsed"

Hi, I am having this issue with my voter board and a Garmin GPS18x LVC. The status page indicates a GPS lock, but the board keeps throwing this warning every 2 seconds or so. I've loaded the SNSRXCFG.cfg and checked that the unit is in NMEA mode. The selected sentences are left as default although I did check and GPGSV, GPRMC and GPGGA are all selected as I read in another thread on here. What other NMEA settings do I need? NMEA 2.3 mode on? Regards Hayden VK7HH