Custom metadata from jt file

Dear support,

I am facing an issue retrieving metadata from jt file. I used hoops c++ functions to retrieve generic attributes (based on sample source code) but some metadata (obviously custom) aren’t retrieved. Hoops Demo Viewer is retrieving them.
Is there a different API (or loading options) to get them?

Thanks
Regards,

Hoops Exchange 2022.SP2.U2 (last supported version for vs2017)
JT Version 10.5