For a longtime I managed to play against bots in Private Match using the mod Bot Warfare 2.3.0.
And I was able to rank-up, gain weapon XP, do challenges, etc.
But today, everytime I make a kill, I get instantly max weapon XP,
and I wonder how I can have a normal progression like before.
I tired to play without the mod, by spawning bots with the console, and even with that, I get instant max XP.
It seems the issue is from the Private Match progression system itself.
I tired on regular servers too and I ranked up normally.