Bing doesn't read my sitemap files, it says they're too large

Hello,
I tried to manually add my sitemap files to bing via their Webmaster Tools user interface.
I receive errors on every sitemap file, it says "The file is too large".
I did split my sitemap files to 30k URLs per sitemap file.

I couldn't find any documented content about their limitations on sitemap file submission.
Does anyone know how to resolve this \ their limitations?

BR,

The easiest thing to do is to just lower your url count to say, 20k and try again.

If you have long "wordy" urls, it adds to the file size.