In the contract, there wasn't any URL address or domain specified. The only wording related to the content destination is "One-time, Non-exclusive rights to use image within the Gerd Ludwig interview piece for Pixel Magazine online blog." I think the problem is as many pointed out - that there was a confusion that the Pixel Magazine blog was hosted on Medium.com. We came up with the Pixel Magazine name very recently, and were also migrating our content to the new @pixelmagazine handle. We used to be @polarrist on medium. This might create more confusion because @polarrist is now all routing to @pixelmagazine now so https://medium.com/@polarrist/where-are-chernobyl-s-children... is pointing to the same article. We added more branding elements (the logo) to make sure this is indeed the Pixel Magazine.
I think the take away from our experience is that, definitely make sure in the contract, specify the URL and domain name.
As we only maintain this one blog, I think the "one time,non exclusive" reflects the spirit of the contract more. We should have just specify that we will only post this in one and only one blog ever hosted on the internet.
We pretty much don't have a place to post this article anymore, until we hear back from NG.