[CA] units cannot be changed to "knots"

[doublewide]

This is a new installation of Axiom Pro MFD and SeaTalk-Seatalkng converter and Quantum Radar in place of E120 and old radar set. The converter is powered from the seatalk spur containing my old pilot, speed, depth, wind.
There is a glitch: I cannot set the speed units on the MFD to "knots" with the seatalk network energized. I can see the pull-out menu with "knots, MPH, KPH" and can click the "knots" but it doesn't change the units to knots, but rather immediately returns to "MPH."
But if I turn off the seatalk network power by switching off the spur containing my old pilot, depth, speed, and wind instruments, then I can set units to knots and it will stay in knots even when I then turn on the seatalk spur.
If I turn off the MFD and power it back up with the seatalk spur off, it stays in knots, but if I power them back up in the opposite order, seatalk and then MFD, it switches to MPH again.
Can this glitch be fixed by altering the power supply to the converter or other hardware change?