Thank you for your answer.
I have only 52 subscriptions and I have been waiting for three days. I have also restart the server once and the plans are still syncronizing.
I created one service plan and two complements. I assigned the service plans to te subscribers and then I wanted to change the configuration of my service plan.
When I accept the changes, Plesk shows "Syncronizing..." near the service plans, but it never ends, so I can change anything from...