Form not displayed to the user

Hello,

I am experiencing the issue with my process:
- The process creates a new user in a specific group and send a mail with credentials to the freshly created user
- The next task is assigned to the user by using a single-user filter (the user id is accessed via a pool variable).

when the new user is logged, the task is displayed but the form is not visible.

Another important point, it only happens when using the process outside bonita studio (deployed on another platform)

If I change the group of the user to match the group of the initiator, the form is visible to the new user.

How can I allow the new user to access the form without allowing the user to start a new process instance ?

Best regards,
Yann