Featured image not displaying in related links

[Jordan Miller]

Hey there, quick question! 

For some reason... the Featured image is no longer displaying when pasting its topic link.

For example, this topic has a featured image of Lana Del Rey uploaded into the OP: https://www.breatheheavy.com/exhale/index.php?/forums/topic/783931-lana-del-rey-serves-old-hollywood-glamour-on-a-music-video-set-announces-new-song-let-me-love-you-like-a-woman/

Featured image:

 

However, when pasting this topic's link in a different thread, the featured image does not display (it used to). Wondering why that could be?