Embed shortcode not working

Hi there.

I’m having issues with the styling of the FEP inbox when i use this shortcode: [front-end-pm]

Here’s what it looks like when I put it on the /inbox/ page:

https://gyazo.com/e6b786f8f4e9de262f21a01b52c5d208

Here’s what it looks like when I add the shortcode to the /my-account/messages page:

https://gyazo.com/a4c7cc41b17c6bd3b1f7b982e3bda3c1

How can I fix the styling on the /my-account/messages page to look like the /inbox/ page?

Both pages are behind passwords, so they are not publicly accessible.