CSS Loaded but not being applied

I know it's already been asked but that person had a typo, and the answer mentioned firebug so it's not current (and is closed).

In WordPress, I noticed that main file, style.css is not being applied, specifically:

• The file IS loaded correctly
• Its styles are NOT being applied

When I inspect element for an element I know is being targeted by style.css, nothing from style.css is there (styles tab of inspect element) at all. I've inspected several elements.

It's loaded through WordPress as so (an unchanged call generated with _underscores):

wp_enqueue_style( 'themexzz-style', get_stylesheet_uri(), array(), _S_VERSION );

This is the produced link (and clicking on it works like it's supposed to):

<link rel='stylesheet' id='themexzz-style-css'  href='http://localhost:8012/themexzz/wp-content/themes/themexzz/style.css?ver=1.0.0' media='all' />

I'm using

• Xampp with php 7.2.3
• with wordpress 5.5.3
• meta charset="UTF-8"
• Database collation is utf8mb4_unicode_ci
• It's an underscores generated theme

Thanks in advance.

@Xhynk - You were right. It was the:

you may have invalid CSS way at the beginning of that file, blocking all the rest of the CSS being applied

As it is an underscores theme and I apply my own CSS from another file, it didn't even cross my mind that there might be invalid CSS in style.css

Thank you @Xhynk