Connecting smarty styles?

Question

PHP

I connect styles like this:
{css file="/os/modules/material/header.css"}
But for some reason the template engine stopped seeing such a connection, and styles throughout the site are not connected. What could be the problem?
The normal connection option works. But this is a crutch, and besides, the connection of styles is scattered throughout the project, changing all of them is not an option.
The page displays this

What could it be?