@nicolas-morissette_6285 ah, that's too bad, but not surprising. Microsoft doesn't like non-Microsoft products (or even products from other departments) using their products 
Unfortunately we can't "see" the response or back/forth communication and have no idea what's going on.
You could attach ProGet to a proxy server (like Fiddler) by going to Admin > Proxy, and see what's the back/forth communication is.
Or , easiest thing, just send us an access key to test with. We can just attach a debugger and see the responses, and maybe even fix the code or work-around whatever nonsense they're doing.
If you email it to support at inedo dot com with the [QA-529] in the subject, we can then attach it to the internal issue, and an engineer can investigate.