I think you might be running into this long running Evernote issue. I’m working with someone else seeing this issue in support, but it’s not widespread and I’m pretty sure Drafts is sending the right information because it works for most every one.
It may be a bug in the SDK code, or something else, but I’m not sure what is different for the people seeing the issue. Is your Evernote account a business account, or is it affected by writing to different notebooks or with different content in the draft?