[CA] [CA11] No depth data on Seatalk NG, shows up fine on nmea 2000 connected devices

[Dustdevil]

Hi Folks,
I'm finishing an install of i50 instruments (wind, speed/depth tridata, EV-200 AP) all networked together via Seatalk NG, with an ITC-5 handling the depth, speed/temp and wind wand.
There is a spur cable out to a nmea 2k backbone that exchanges info with a Vesper AIS and Garmin plotters.
The issue i'm having is that depth will not transmit through the Seatalk connected devices, but shows up on the Garmin network just fine.
i swapped for a known good depth instrument through the network with no joy. I wired the transducer to the depth directly and connected through the ITC-5, and the instrument would read depth, but the Seatalk network devices all still showed 3 dashes. When wired as intended the ITC-5 shows a green steady LED for the depth transducer. Bypassing the ITC-5 with the transducer connections verifies the transducer working.
I've disconnected the nmea 2000 spur to see if it's a terminator issue with no change as well.
Ideas?