preg_replace is the culprit. As you would see in the theme’s source, I’m using HTML_OK (HTML Overkill) to convert an array into HTML markup. I already removed preg_replace and everything’s back to normal (check out the test case below).
I tried using OB in Twenty Seventeen theme and it’s working just fine. I have to find the culprit in Applicator.
Hello... from below!
If “from below!” is in the same line as “Hello…” then I suspect Output Buffering has something to do with it.
It’s supposed to have 4 line breaks from “Hello…” because it is inside the <pre> tag and I intentionally put those line breaks as formatting.
I’m currently sorting this out in the Make WordPress Core.