It seems that I am getting this problem since version 1.18, honestly I don't remember.
With VSCodeVim installed I used to press the = key to get my code (Elixir, embedded elixir, ...) indented properly.
Am I missing something, like a configuration, that would allow me to re-indent my files without having a nagging "Formatter for file x not installed".
This is honestly the only things that nags me with VSCode so far, love the speed, the capabilities and the UI...
Just posting my comment as an answer
Try using the reindent lines command. This command should work for many languages even if you don't have a formatting extension for that language installed