model-viewer texture swap / variant quantity

I was creating a simple 3D visualizer for a product. I went to the model editor page and exported the file with all its variants, as I needed to swap to different textures.
Then I proceeded with importing it into my page, as shown in the examples on the website, only to discover that the variant change function ( the example with the running shoe on the website ) didn't work anymore because there were too many (?). I had 25 variations; they were all present in the model, but the texture files didn't load on change. Only the first two and the last one did.

So I decided to implement it in another way through the example of the helmet.
I made some tests, and it seemed to be working just fine. The problem lies in the fact that I can use ONLY textures from the same URI as the example. I tried downloading the textures from the example URI and using them locally, but it's not working. It gives me an "Uncaught (in promise) Event {isTrusted: true, type: 'error', target: null, currentTarget: null, eventPhase: 0, …}" error, which doesn't make any sense.

I tried searching the documentation and I couldn't find anything, I tried searching online and nothing. The html part is identical to the example on the website, I only removed the options I don't need.

Can someone please tell me what's wrong? Or a way to use the variations system?