iTC-5 log accuracy

[billc42]

I've installed an iTC-5 to connect my wind, speed and depth transducers into my network. This allowed me to remove five wires from my helm pod and replace them with one STng cable when I upgraded to p70, i50, i60, i70. Every time I turn off my instruments, the iTC-5 is dropping the tenths value from the log (distance). If I travel 15.6 NM, after I turn my instruments back on the log reads 15.0 NM; .6 is lost. If I travel another 20.8 NM, the next time I turn my instruments back on the log will read 35.0. The .8 is lost, now totaling 1.4 lost. If the average distance tenths value is .5, that means after 10 cycles (perhaps days, trips or legs) of the power switch I could be losing 5 miles. If power is cycled 100 times (a short season), that's 50 miles my log is missing.
The issue is with the iTC-5. The i50 Tridata, i70 and e95 all reflect this loss. The only thing impacting this is power to the iTC-5 as powering any of the other devices does not drop the tenths.
Will there ever be more updates to the iTC-5? My iTC-5 version is at v1.12 (2014).
Thank you.