Now this might be because I'm running Tale of Two Wastelands but I'll take a shot anyway.

I played many hours of NV years ago but never quite finished it and decided to kill two birds with one stone by installing the above mod so I could also finally do the DLC for F3 while finishing the main quest for NV.

So most of the achievements seem to be working - I picked up Jury Rigger no problem;You run Barter Town, Ol Buddy ol Pal, Crafty, and No Tumbler Fumbler. But New Kid (reaching level 10) has not triggered in spite of reaching levle 15.

By design, achievements don't become acquired if you are running cheats during the same time when your character reaches their requirements (i.e. if you turned on godmode in the console and then reached level 10 before you exited & restarted a new session of the game). So something like that could be what stopped it.

Maybe the game considers certain mods to be cheats as well and applies the same rule when they are running. But I'm not sure about those things so I'll let someone with more knowledge about that discuss it.