Based on my research, Mendix does not support dynamically updating a navigation item label at runtime. Since the navigation document is static, it’s not possible to safely bind a label like “Notifications (3)” after login. While DOM manipulations via JavaScript may work in the short term, they can become fragile and lead to UI issues after Mendix/Atlas updates or in different theme and browser scenarios.

A more robust approach is to handle this at the layout level instead of the navigation item itself. A separate “Notifications” area can be placed in the same region as the menu and styled with the same CSS so it visually behaves like a menu item. The notification count can then be calculated after login or via specific triggers and bound through a non-persistent object or datasource. This avoids the need for JavaScript, stays within Mendix-supported patterns, and results in a more stable long-term solution.