Each Labor & Equipment row shows an Assign employees picker (with the hint "Save first to assign" on unsaved proposals). In the current version the picker is present in the interface, but the background endpoint that stores the assignment could not be found in the reviewed code, so the selection may not persist. If you rely on staff assignment, use the Tasks tab (Employees Tasks) to assign staff to the event instead, and check with Sprwt support whether labor-employee assignment is enabled on your account.