additional-location not working with yaml formatted files

Question

In my java spring boot project, I have an application-dev.yml file in which there is:

spring:
  config:
    additional-location: classpath:*-{env}.yml

and another file teacher-dev.yml in the same path in which:

teacher:
  name: adam

With use of @Value("${teacher.name}"), the project is failed to run by the exception

Could not resolve placeholder 'teacher.name' in value "${teacher.name}" 

However, it runs OK if I revise the teacher-dev.yml file as:

teacher.name: adam

I have checked the document but seems no hints there. How do you resolve it while keeping the additional properties in yaml format to make the project work?

The spring version is 2.7.18.