Custom skin materials are not saving, despite attempting several times.

Issue persists through restarts, the materials editor simply refuses to save my changes and any changes fail to show up in game.

So I've been trying to make a slightly modified version of the Itasha livery for my little head-canon car called "Natasha" which is basically the BEA Racing No 4 car instead of No 3, and thus I'm trying to make a custom livery with the existing Itasha files, simply modified to suit the livery.

But its just refusing to show up. I fix it, and then save, and it doesn't show up. I try swapping the liveries around with the parts editor, then go back to the materials editor, lo and behold its reverted to this broken version of the material using an older filename I was using. I've investigated the other steps 10 times over by now, and the only issue I can find is this. I have no idea why its doing this and I have no clue how to fix it.

Currently attempted troubleshooting:
Remaking the Json from scratch
Renaming the Jbeam to its original name (Simply breaks the metallic map)
Incorrect Materials map:




Corrected Material:

Message confirming save



But then nothing.

Jbeam file

Json File:

Gets the all clear from the Json checker. I have noticed that it doesn't seem to update when the material editor saves. Not sure whats up.

Error log clearly shows that the images with the wrong file directory aren't loading, but then is fixed when I swap the livery over. But again, when I check the material editor it reverts and spews errors again.
Really, truly, stumped by this. Was supposed to be an in and out 20 minute modding adventure for fun that has spiraled into an hours long mess of troubleshooting.

 

Ok figured out the saving issue, it was a mistake on my end.
When I changed the name from Bea-RNo4 to Natasha for simplicity, it resulted in 2 materials files generating which both controlled the livery, meaning that when the game saved it tried to save to the materials file for "Natasha," but when loaded it would load the Bea-RNo4 version. Basically, it would save to one and load from the other, making it appear like it was failing to save. Clearing the cache fixed it, and now I need to figure out why the livery still isn't loading. I'll run through the tutorial troubleshooter one more time and see if that fixes the livery not loading.
--- Post updated ---
Right, so the saving issue is definitely fixed. Unfortunately, it didn't actually fix my livery not loading.
This is my current setup for the livery.



So I'm not exactly sure whats going wrong. I thought I had validated the Json correctly (and the tool does say its fine), so I'm thinking I somehow messed up the main material code when copying it over or something.

Alternatively it could be fighting because the materials file is named "main.materials.json" and that causes a conflict with the actual main.materials.json ingame. Not sure, I'll try clearing cache again and changing the main.materials.json name to Natasha.materials.json and see if that fixes it.
--- Post updated ---
Didn't work. Any advice or help would be greatly appreciated.