I have a document that I can view by accessing Weblink directly going to the https://servername/weblink/DocView.aspx?id=23620695&dbid=0

This shows as expected:
https://www.screencast.com/t/NGHKK1M0CwG

If I inspect this page, I can see the thumbnail view can be seen by going to the url: WebLink/ThumbnailImageData.aspx?dId=23620695&pageNum=1&dbid=0

My browser does not open this thumbnail as expected:

I am looking for it to show like:

But I cannot figure out why it's not working.  

Cheers,

Nate