Not sure if this helps at all, but I made a further edit to the code to use a Serial.write as well.
uint32_t statkal = (((notifydata[4] << 8) + notifydata[5]) << 8) + notifydata[6];
uint32_t statdistance = ((notifydata[7] << 8) + notifydata[8]);
uint32_t statstep = (((notifydata[9] << 8) + notifydata[10]) << 8) + notifydata[11];
uint32_t stattime = ((notifydata[12] << 8) + notifydata[13]);
char buff[100] = "";
sprintf(buff, "Data - Kcal: %lu Time：%lu Distance：%lu Step: %lu", statkal, stattime, statdistance, statstep);
Serial.println(buff);
Serial.write(buff);
Serial.println();
As you can see, there is no consistency here, buffer used in both the println and the write are the same.
