'Degenerate Mass on Follower Side' issues?

[Please refer to the screenshots, as the portal does not allow attaching Simulink (.slx) models here] * EDIT MADE TO QUESTION: NEW MODEL ADDED HAVING SAME PROBLEM

Because there is no pre-made joint which gives 2D translational and 3D rotational freedom, I used a combination of rectangular joint and spherical joint, to model the interaction of tire patch and road surface (2nd picture). This combination joint has legitimate mass on both sides, but Simulink Solver apparently requires another mass in between them, i.e. between Rectangular and Spherical Joint. I can put a dummy negligible mass (at the cost of slower simulation) to overcome this problem, but I want to understand why is this issue occurring? Isn't a Planar Joint a combination of Rectangular and Revolute Joints, why can't I approximate a custom joint using two joints without having a mass sticking in the middle?

[Swarooph]

You can save your Simulink model as a .mdl by using the File --> Save As option and choosing .mdl as shown in the screenshot below.

Can you attach a model that way? Way easier to debug issues when we have the model.

[Surojit Sen]

Hi Swarooph, thank you commenting, sorry could not respond earlier as comments do not send email alerts (didn't check comments before). Anyway, I have attached another model now (different from screenshots) which has the same problem. There is only one mass attached (CoG) which is being acted on by various forces via different joints and transforms in the middle. I have tried to resolve by putting a negligible point mass (0.001 kg) as the wheel graphics, but in vain.

Thanks for taking the time out.