No congratulatory messages could be found.
On some days, there may be no congratulatory notifications on LinkedIn.
Navigate to the LinkedIn notifications: https://www.linkedin.com/notifications and check if there are any congratulatory messages.
Otherwise, take a look here:
https://www.linkedin.com/celebrations/birthdays
https://www.linkedin.com/celebrations/work_anniversaries
https://www.linkedin.com/celebrations/job_changes
If it looks the same there, you currently have no contacts displaying congratulations.
Otherwise, take a look here:
https://www.linkedin.com/celebrations/birthdays
https://www.linkedin.com/celebrations/work_anniversaries
https://www.linkedin.com/celebrations/job_changes
If it looks the same there, you currently have no contacts displaying congratulations.

Alternatively, you can also display more congratulations in the settings.