It's because of how Cheetah operates. If you upload a YouTube video, then share that YouTube video to Steemit, Cheetah won't recognize it as copycat material because it's posted so close to the original time of upload. The same effect applies to SteemPress, which also does the verification thing automatically to a degree. Just look at any one of my posts and scroll to the bottom to see what I mean. It'll say it's "posted from my WordPress blog LinkHere".

The issue arises when you post older content from your blog.

If you had issues with SteemPress in the past, give it another shot, it was super easy to set up.