Getting I2C working with CTI ASG008 Sprocket carrier?

Okay, so this is a fairly specific problem I’m having, but wondering if anyone else has had a similar issue. I’m trying to interface an AdaFruit Featherwing for servo control (this thing) over I2C bus 0, with a TX2 on a CTI ASG008 “Sprocket” carrier board (this thing).

As far as I can tell, everything is hooked up correctly, the Featherwing is powered at 5V for motors and 3.3V for logic, solder jumpers are set for address 0x44, because there’s something already at 0x40 (no idea what), the correct I2C pins are connected to bus 0 on the Sprocket. But when I run “sudo i2cdetect -y -r 0”, I get:

.    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: UU UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

The device isn’t showing up at all. Could someone suggest next steps, in terms of troubleshooting? I don’t happen to have a logic analyzer or scope handy (and frankly wouldn’t know what to look for if I did), but wondering if anyone else has managed to get I2C working on a Sprocket board under L4T 28.2 on a TX2, and what did you do to get it working?

thanks,

It’s better to get support from vendor, you can contact them here: http://connecttech.com/support/