Microsoft project management software used to plan, manage, and communicate a project schedule and other information among workgroup members, project managers, and other stakeholders.
Dear respected Khaldoune Karim,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
I’m sorry you’re having a problem and for the situation you encountered, we deeply understand the inconvenience caused and apologize for it.
As per your description, it seems that the issue also occur to other user as well and you checked all the synchronization settings is correct. I'm afraid this issue could be a temporarily server-side issue which needs to be investigated via remote section and collect logs and fixed from back end.
I would suggest you raise a support ticket from the Microsoft 365 admin center and report the issue to the related team. The more reports they receive from different customers, the more likely they will be able to find something affects users in common, do investigation and fix it soon.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Note: To create a support ticket, you need to have Microsoft 365 admin privileges and if you aren’t admin of your Office 365 organization, please contact the admin of creating a new ticket.
Reference: How do I find my Microsoft 365 admin? - Microsoft Support
Please accept my Apologies for redirecting you to the related team support as the moderators in this community have limited resources to check the backend information, and to get the fast and better assistance we requested for it.
I'm sorry and I apologize for that.
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Waqas Muhammad