ERG issues with Tacx Flux S

Hi,
I'm using TrainerRoad on Android with a Tacx Flux (1st generation, updated to the latest firmware using Tacx's app).


The trainer is connected using and ANT+ stick (Garmin) and I also have a heartrate belt (Garmin) and a power sensor (Power2Max). I'm using ERG mode.


For the last 2 trainings I had this issue : the training goes well up to ~45 minutes then when the app ask for a recovery slot (~120W for example), the trainer stays to 200W for some time. Then when the app asks for 313W, the trainer seems stuck at 300W with very strange behavior (like waves on the power) making the training impossible to follow.


I checked the trainer and the belt is mounted properly and I don't have strange noises.

Do you have an idea of what could be wrong there ?

thanks and best regards
Eric