GLFM markdown Includes DOESN'T render by using ::include{file=other_README.md}

Here I have two sets of self-managed gitlab community edition running on v17.5.x and we are using gitlab flavored markdown’s Includes function to let render inside one README.md for other md files by format “::include{file=example_file.md}, but in preview mode inside gitlab’s MR, we can’t see real rendering effects. Any limitations or wrong format we met?