Clion is not automatically completing braces or giving auto-completion suggestions if I have a project with multiple languages opened

When I make a new project from scratch and choose c++ executable, then the editor works perfectly fine and my the parenthesis are paired automatically, and auto-complete suggestions are also given. However if I download a repository already containing code in 2-3 languages (for eg: few files of c and few files of bash), and open it to edit a c or c++ file, the editor just doesn't work like a code-editor. Neither the braces get paired, neither I get any suggestion, nor the next-lines are indented. I have already checked the editor settings, bracket-pairing, line-indents, everything are already enabled.

I am using clion on opensuse tumbleweed. How to fix this?