Cross trainer + Zwift: Avatar doesn't move


I use a cross trainer (Maxxus cx 7.8) and Zwift, but my avatar doesn’t move.

The crosstrainer is connected and shows speed as 0 zero, speed I transmit from an android device using treadmill speed transmitter app, and it is connected and show cadence value as NOT zero.

Why speed is shown as zero from the crosstrainer? on other app, like kinomap etc, speed is correctly transmitted from the trainer