Toggling BOLD on Headings in Post Excerpts: Is this a bug? (do you see it too?)

Site URL: https://youtu.be/43a697rHrgk

Hello. When toggling BOLD on text headings in Post Excerpts, the heading text is behaving in the opposite way that you would expect. I've seen this a few times, and have ignored it, but recently when showing a client how to do specific text edits that are critical to the outcome of the post, it became confusing at-a-glance. (see video link)

Can you reproduce this?

In a post excerpt: 

1. Type any text, select the text, and convert the text to a heading by choosing "h3" (or h2, h3) 

2. Select the text again. With text selected, make the text bold by clicking "B" in the interface. You will see how when BOLD is applied in the UI, the text appears UNBOLD. When bold is unapplied, the text returns to appear bold. 

See video: https://youtu.be/43a697rHrgk