I see! Thank you very much for your reply and for having highlighted this criticality. I may have found the solution to the problem of possible shaft slippage without even wanting to.
Also, I would like to take the opportunity to quickly ask a couple of other questions:
1) Why is the pin completely undeformed? Is there an error or do you think it could be physically accurate? If it is an error how can I fix it? Using bounded contact instead of friction?
2) How could I improve the mesh of the target body? The automatic methods are not applicable so I need an alternative strategy