Power data looks correct in Garmin Connect but missing in exported .fit file

Yesterday I equipped my bike with a new spindle power meter, the sram rival axs dub-pwr. I had a zwift workout this afternoon, and data is recorded in 2 ways simultaneously: a)PC(Zwift), bluetooth, power from Magene T100 power trainer, cadence from garmin cadence sensor; B)Edge 530, ant+, power/cadence from dub-pwr. Both are synchronized to my Garmin Connect account.

Power and cadence data for a) and b) are both well displayed on the Connect site, I clicked 'Export Original' to download .fit files. 

I attempted to visualize them ,via fitparse, matplotlib(python), for data a) it works fine, but data b) seems to be empty.

Any idea?