I posted this yesterday, and now it's gone. So I'll try again:

Hopefully someone here can assist. This is working in production, but not in sandbox.

I'm getting the dreaded 10007, "Sorry, something went wrong. Please wait a moment and try again."

Any guidance or assistance would be greatly appreciated :)

 <ItemID>xxxxxxxxx</ItemID>
 <PictureDetails xmlns="urn:ebay:apis:eBLBaseComponents">
 <PictureURL>https://ourdomain.com/somepicture.png</PictureURL>
 <PictureURL>https://ourdomain.com/somepicture2.png</PictureURL>
 </PictureDetails>
 </Item>

On an unrelated note:

Apologies for the formatting above. I tried pasting my XML request into a "code" block in the post editor here, but your editor keeps mangling things with HTML entities in code blocks. Would be great if you could fix that, too :)

I then tried to upload an image showing the XML, and that gave me more errors in the browser console:

/cropUpload.json:1 Failed to load resource: the server responded with a status of 401 (Unauthorized)

edit.html:1 Refused to apply style from 'https://forums.developer.ebay.com/questions/31036/css/bootstrap.min.css' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.

combined.js.h-2014687796.pack:1 POST https://forums.developer.ebay.com/cropUpload.json 401 (Unauthorized)