If you use the Upload to album option when posting, the image preview does not appear. Looks to be a pathing issue.

<a class="view-image" href="/mvcPhotoAlbum/GetPhoto/5619" target="_blank" rel="noopener">
<img src="/mvcPhotoAlbum/Thumbnail/5619" alt="" border="0" loading="lazy"></a>

There is a missing / after "mvc" in the path