Inconsistent markdown-> HTML conversion

I’m drafting an article using Middleman (with blog extension), and for some reason markdown is converting to HTML in a very inconsistent way when I run it locally by running middleman server. I’ve tried restarting the server a few times and the problem persists. I haven’t tried deploying it yet and seeing if the problem persists live.

For example, my first h3 tag is showing up as “###” instead of converting into an h3. But further down the page, I have another h3 tag that is converting just fine.

h3 not converting

Elsewhere in my article, I have **strong text** showing up as *italicized with asterisks*. And even **strong text** showing up like this: word**. But in most cases, **strong text** shows up bold like it’s supposed to.

Any ideas what could be causing this? I’ve published two previous articles without any problems.