Tailwind classes working inconsistently, why?

This might be an obvious solution, but I just don't get this inconsistent behavior from Tailwind.

I'm doing a website layout, and when I use some values for utilities like margin, space between or font size, it works fine, but then I try a different value and the class doesn't have any effect. For example, when I use mb-32 here, fine:

<div class="flex flex-col mb-32 space-y-12 md:w-1/2 md:mt-0">

            <h2 class="max-w-md text-3xl font-bold text-center md:text-5xl
            md:text-left">What's different about Manage?</h2>
            <p class="max-w-sm text-center text-darkGrayishBlue md:text-left">
                Manage provides all the functionality your team needs, without the
                complexity. Our software is tailor-made for modern digital product
                teams.
            </p>

</div>

I want the space to be a little shorter, so I use 28, 24 or 20, and none of them work:

I'm using Live Server btw, might have something to do, as some things I was trying yesterday that didn't work are working now.