Unfortunately I will not be able to help without some more details about the model. A couple of the common erros that the legacy platform does not catch (but are now caught using the new ShapeDiver 2.0 beta platform):
Your model might be using an exotic font (in text panels or tags) that is not installed on our servers. Make sure to use standard fonts everywhere unless required by your application.
The loading time for your model might exceed the computation limit on your account. I am sure you are aware of the computation time limit that comes with your account, however it is also important to pay attention to the time it takes for Grasshopper to open your model for the first time, because this is typically what our servers do. If the opening time exceeds the limits of your account, the upload will likely fail.
If none of these hints seem to apply to your case, please try to create a minimal example that you can post here for me to investigate.
