I’ve got a reproducible glitch: without a timestamp the value is fine, add a timestamp and the Y value shows up as a hex.

// OK → numeric shown correctly (e.g., 25)
gT1.SendData("temp1", (float)t1_C);

// NOT OK → arrives as hex
gT1.SendData("temp1", ts.c_str(), (float)t1_C);

Targeting this per ...