notice something strange today during a WTRL duathlon race i was participating in. The watts readout in the upper right “seemed” normal relative to my effort however the w/kg in the “riders nearby” list was way off. In fact it appear to be inverted, as in during a hard effort it was indicting a low number and them when riding easier it indicated a higher number. i have heard this being atributed to a few second lag in the w/kg display bet this seemed far more consistent (and was off by several watts). i have included a picture to reference the fields. What the image doesnt do is show the error, which i didnt capture since i was kinda busy racing 
According to me, the power data in the upper left corner is generally averaged over three seconds, while the one on the right is averaged every second.
which, for the record you can set in options if you want to have that top left wattage show immediate… although, most folks don’t because it’s going to be quite all over the place.
averaging wouldn’t explain why when i hold 4 w/kg for longer than 3 second its reading 1.9 w/kg. Its also interesting to note that while i have the wattage set to three second average, it seems to bounce around more than the w/kg (though not by an amount large enough to change the w/kg by 2).
is your weight set incorrectly or something?
hummm can imagine a scenario where setting my weight incorrectly would cause w/kg to display out of sync in this manner (low when it should be high and high when it should be low), though i did recently drop my weight by .2 kilos, and i did notice that zwift only displays the whole number in the game UI. That said if it was just my weight that was high or low it would just be off in one direction, not one direction when putting out low power and a second direction when putting out higher power.