Hey there,
I am really sorry for the delay of this reply as it is a weekend for us here.
Can i have this 'HNBadmin' user login access? If other user unable to see that preview image, mean this 'HNBadmin' also unable to see that image as well.
Based on what i checked, it seems like that image link unable to load, this is that image link :
[gist type="php"]
https://scontent-lhr3-1.cdninstagram.com/vp/0e8c1b4ca5d953063492772870ccdaff/5BC86732/t51.2885-15/e15/41791714_310784906410412_3497643979418107904_n.jpg
[/gist]
By the way, i did tried share that instagram link in my locally, it seems like now this instagram post changed to use this cover image.
[gist type="php"]
https://instagram.fkul14-1.fna.fbcdn.net/vp/20ec9f4c7cd55a8219eaf671a76c00e7/5BCDAD32/t51.2885-15/e15/41791714_310784906410412_3497643979418107904_n.jpg
[/gist]
If you do not want to re-share this post in your site, perhaps you can update your site database access so I can help you change to this image link.