There are seemingly a few issues with the editor again @Brando
When copying and pasting text from other parts of the editor, it’s like it has a mind of it’s own.
Dropdown selector on internal page links also won’t let you scroll with the mouse, it just disappears.
Using Chrome Version 68.0.3440.106,
High Sierra version 10.13.6 on Mac.
Thanks so much for posting and for the detailed video showing the issue.
Using the steps you provided I was able to see the error on my end as well. I’ve reported it to our Content Editor team and we’ll start investigating a fix for this.