Direto resistance issue

[davidberczi]

Dear support team!

I've just bought a used DIRETO (1st generation).
When the previous owner showed it, he used the MYELITE app in power mode. Worked fine. Adjust to 300W+, hard to pedal, okay, it works, i thought.
I noticed the following:
Using zwift: I tried to do the FTP test. There were different Wattage levels before the ftp itself. These were fine.
FTP section started, and crazy things appeared. Resistance practically gone away. Wattage on screen went 500-2000.
I also tried training in MYELITE. If I start calm pedalling, no problem. If I want to accelerate, it loses resistance and shows crazy high Wattage.
Here is my fit file from zwift:
https://www.dropbox.com/s/y9d6fmjwmeptrdf/2019-12-01-20-46-16.fit?dl=0

I tried BT, Ant+. ERG ON, ERG OFF.
Calibrated in MYELITE, difference is 3 only, so belt tension is OK i guess. Power smoothing is 5 at the moment.
Circumreferene 2070.
Also switched from PC to another W10 i7 machine and phone app as well.
Please help, I really want to use this trainer and having fun at last.