Subject line doesn't show up in the window

[ILoveSkilledCoders]

Hi there,

It's hard to explain, so here are images.

While the subject line shows up when I'm looking at the email, here it's not showing up & that concerns me that it won't show up on the other person's side.

https://i.imgur.com/9YVkvvB.png

I should see the subject line when looking at all of my mail windows that are open in the list.

https://i.imgur.com/17XLDvn.png

Thanks