Wrong opacity in picom

I am trying to customize my cwm using picom for some tweakings.
The problem is when I try to setup opacity for active and inactive windows.

This is my relevant config section:

inactive-opacity = .5;
inactive-opacity-override = false;
active-opacity = .9;
inactive-dim = 0.0;

I am using Xterm, but only the active windows behaves normally with .9
opacity, the inactive ones are just not transparent, like inactive-opacity
= 1. Is just like they act oppositely as they suppose to.

I even tried to use some rules I found on an arch wiki

opacity-rule = [
"90:class_g = 'Xterm' && focused", "60:class_g = 'XTerm' &&
!focused"
];

but nothing works.

I am using OpenBSD 7.0 stable.

Thank you for your help!