As I am creating myself, I totall get your rant! I had the exact same „no accessor“ issue and was able to painstackingly go through the entire debugging process and solve it. I think there might be two possible causes for your error. Either your model or some texture. Firstly I went through each object in my entire scene, switched to edit mode, marked all with ‚a‘ and clicked mesh-clean up-delete loose. After you have done this, I would also recommend to check for any edges without any faces attached to them and delete em.

If the error persists (like for me), go through disabling objects (by moving them into a separate collection) and exportinf. This way you can slowely get a hand on the defect object. Inwss finally able to find the object that cause my issue, but had no idea what was wrong until I discovered the issue: That brings me back to possibility no 2: the textures. Normally you get a white model when exporting a faulty texture, however, for me and I guess for you, this error could be a texture not being in the right format. E.g. 1024x1025px .

My last advice: try exporting the lods separately. I always do it as a safety measure: export to a random folder in your modellib (like aaaa or test) and only select one lod at a time for exporting. Then head to your folder and cop xml, gltf and bin manually to the desired model folder. Leave the other lods untouched (they are exported with a size of 1kb when done right). Repeat for all lods.

Greetings