Hello Olivier,
Which version of Ansys are you using? Have you tried the latest 2023R1?
It is difficult to troubleshoot this type of problem without having the model. Ansys employees are not allowed to upload and download files on the Ansys Forum.
It would be best if you could create a service request (SR) on the Ansys customer portal for this issue:
support.ansys.com
Let me know how it goes.
Reno.