Check the vehicle speed source under APP SETTINGS, then Unit and Values. It can be set to ECU, GPS or wheel speed, and if it is set to a source your car does not provide, speed reads zero while every other channel works.

RPM arriving proves CAN is healthy. So a missing speed reading is almost never a wiring fault, which is where most people waste their time.

Check in this order:

1. Vehicle speed source. Set it to a source your vehicle actually provides.
2. Tire and wheel data. If speed is calculated from wheel speed, wrong tire data gives wrong or zero speed.
3. Debug Data View. Confirm whether a speed channel is arriving at all.
4. ECU side. Confirm the ECU is broadcasting vehicle speed. Many standalone ECUs do not unless a speed sensor is wired and configured.
5. GPS. If the source is GPS, confirm the unit has a lock.

Related: Units and Values: Metric, Imperial and Display Formats · Tires and Wheels Setup · My GPS Does Not Lock