Custom sounds not working; default test engine playing instead

I've been working on a mod that recreates multiple Honda motors. So far, it's worked flawlessly, up until about two hours ago. Suddenly, none of my sounds were working; they seemed to have reverted back to the default engine sounds. And now, two hours and a completely reinstalled game later, I still haven't figured it out.

materials.cs:

Code:

singleton SFXProfile(b16s){
   fileName = "vehicles/DelSol/art/sound/b16s.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b16t1)
{
   fileName = "vehicles/DelSol/art/sound/b16t1.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(k20s)
{
   fileName = "vehicles/DelSol/art/sound/k20s.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(k20t1)
{
   fileName = "vehicles/DelSol/art/sound/k20t1.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(k20t2)
{
   fileName = "vehicles/DelSol/art/sound/k20t2.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(k20na1)
{
   fileName = "vehicles/DelSol/art/sound/k20na1.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(k20na2)
{
   fileName = "vehicles/DelSol/art/sound/k20na2.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b18s)
{
   fileName = "vehicles/DelSol/art/sound/b18s.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b18t1)
{
   fileName = "vehicles/DelSol/art/sound/b18t1.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b18t2)
{
   fileName = "vehicles/DelSol/art/sound/b18t2.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b18na1)
{
   fileName = "vehicles/DelSol/art/sound/b18na1.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b18na2)
{
   fileName = "vehicles/DelSol/art/sound/b18na2.ogg";
   description = "AudioDefaultLoop3D";
};


singleton SFXProfile(b18na3)
{
   fileName = "vehicles/DelSol/art/sound/b18na3.ogg";
   description = "AudioDefaultLoop3D";
};

Exerpt from one of my engines:

Code:

    "engine":{        "idleRPM":850,
        "shiftDownRPM":4500,
        "shiftUpRPM":8000,
        "maxRPM":8400,
        "inertia":0.08,
        "friction":16
        "brakingCoefRPS":0.15
        "burnEfficiency":0.5
        "throttleSensitivity":1.2
        "torqueReactionNodes:":["e3r","e3l","e2l"]    
        //sound things
        "engineSound":"k20s",
        "pitchFactor":0.93
    },

Am I missing something here? The sounds are all placed in /vehicles/DelSol/art/sound/ and were working for quite a while - I've recorded videos of them - then suddenly stopped working... The debug code in custom_sounds.lua also happily reports that (for this example) it has loaded the k20s sound profile, yet it still is the default engine sound. And it does this for every different engine I've made, all using different sound profiles. I am absolutely stumped and my progress on the mod is in hiatus until I can figure this out :/


Edit: Woke up, copied all the new files from this bugged zip into an old backup version zip and for whatever reason, that seemed to fix it. Mods, lock and/or close this topic please?