Garmin Cadence Sensor

Hello. I have a Garmin 2 Cadence Sensor and also a speed sensor and I also paired it with my watch( also garmin). On Zwift no matter how fast I pedal, the rpms are not going higher than 70, while on my watch it shows 88-90-100, so the difference is that compared to zwift my watch shows about 10-15 more rpms. What should I do? (The cadence sensor is positioned well on the crank arm)