You will need to verify if you have project budget alerts enabled. First, let's understand who can receive budget alerts and how can you set up a user to receive them.
Who receives project budget alerts?
For projects with the budget type of Project Fee, Project Hours, and Category Hours; the alert is received by active project members that have the 'Project Manager' or 'Administrator' role assigned at the Contact level.
For projects with the budget type of Person Hours, the budget alert is received by active project members with the 'Timesheet Entry' role assigned at the Contact level and timesheet entry is allowed checked on the project. Budget alert notifications can be switched Off or On for any project member by unchecking the “Receive Project Budget Alerts” checkbox on Project Members edit popup.
A user can also switch on/off all project budget alerts by toggling the “Receive Project Budget Alerts” option from their user profile page.
You can learn more about Project Budget Alerts here. If you still are unable to receive project budget alerts, please feel free to reach out to our Support team and we shall investigate it further for you.