Why doesn't wkhtmltopdf page-break-after have any effect?

Possibly unrelated as your pdf generated ok with an earlier version of wkhtmltopdf. Either way, I had similar issues with page breaks not being applied correctly. My problem was parent elements of the page-breaked element having an overflow other than visible. This fixed my issue:

* {
  overflow: visible !important;
}

Of course, you can be more specific about the tags this applies to ;)

try using as follows

 <div style="page-break-before:always;">
   //your content
</div>

this should work.

I am usinf wkhtmltopdf 0.12.3.2

For me page-break-after works when a border is set, and when the breaker div is an immediate child of body.

.page-breaker {
    clear: both;
    display: block;
    border :1px solid transparent;
    page-break-after: always;
}

break-break-before does not work.

--print-media-type not needed.