Bold Text Displaying in Editor, not in post preview

Hi all.

Having a bit of trouble getting text in my post to bold. It shows up bolded in the visual editor, but when I preview the post, the text isn’t bolded. It does look slightly different, so maybe something is going on that doesn’t quite look the way I want it to, but for all intents and purposes it’s not bolded.

I’ve tried adding custom CSS linked to the strong tag, but no luck.

Any advice?