I encounters a problem today when trying to upload to Substance Painter and this was that my model and texture set were to large for sketchfab to upload. I went back through all my presets and realized that some of them were off so it was exporting a ridiculous size. I quickly went back though the process again and was able to upload it without any errors.
As I was able to upload this variation of the model, I began work on my second model which is the mini-turret.