Hi @Oliver Guo - I'm still out of the office for a few more weeks, so I'm not following any reccent changes / issues. I think the quickest resolution of this issue would be to open a support ticket. They can escalate to the product group if it turns out to be something we need to look at or fix. Sorry.
We experienced the same issue today, and after some testing using different tools found out that "User-Agent" header is required when doing a request. When doing a httpclient request using c#, this was not included as default, and had to be added manually:
_httpClient.DefaultRequestHeaders.Add("User-Agent", @"Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36");
the User-Agent could be whatever, but we used chromes.
Hi Oliver -- we had an issue in the REST API that was introduced last week. A customer reported it to us last Friday around 14:40 UTC, and we had a fix in production at 15:20 UTC.
While we do keep an eye on the forums for support issues like this, it's best to open a support ticket with CSS. Providing a network trace (Fiddler or .HAR from Edge or Chrome) right at the start helps us quickly identify what's happening.