I checked the i2c source code. There's internal PULLUP already. We also tested the original sketch for sensor. It works fine. Could you please show the sketch you tested?
The schematic place an old ESP-12 module. That's a little difference with ESP-12F. The GPIO4 and GPIO5 are swapped. But in fact, we use ESP-12F with the sensor. We'll replace the module in the schematic. Thank you very much for mention about this.