No resistance at all Tacx Desktop app movies

Hello everybody

During training I have no resistance during some films (use Tacx Desktop App). In one film I have to use one of my lightest gears to continue cycling/ reach the top. There I also feel the different slope changes during the ride, for example, at the hairpins. But in the other movie I easily cycle in one of my heaviest gears up a 20% slope which feels no different than a 10% slope from that movie. My wattage here is also 1.5 W/kg instead of, for example, 3 W/kg.

Does anyone know what could be causing this?

Reaching the top of the Stelvio in heart rate zone 1 or 2 (see adjustment) is something that I will not succeed in real life. But via my Tacx Neo 2 it is!
And if I want to go "up" with a larger wattage, I have to adjust my cadence to 120rpm in my heaviest gears.

Because of training for the Amstel Gold Race and a Dutch fundraising event on the Alpe d'Huez, quite frustrating when the resistance doesn't adjust.

Thank you for your responses