Bing is now working at least for the basic cpp API stuff, maybe the sitemap was intermittently working on their last scrape. For an example of something working on Bing that is missing on Google search both for:
unreal engine tarray removeat
Since this sitemap stuff is cached with cloudflare, check cloudflare settings for something like what’s going on with this:
While that’s rss, rss uses xml too like the sitemap.
This one for example, with all the cpp pages indexed, still doesn’t load for me and gives a cloudflare timeout: