The consistent condition that I have noticed that seems to cause, or is related, to this is the one I described above, viz., this tends to happen when I have inserted a hyperlink as the first text in the body of the document (usually, I have a centred, bolded title, but then go into the body of the document, and insert a hyperlink).
*What is the method being used to do so?
Are you pasting the link as URL into the text editor plain, and letting the web link auto-detection code turn it into a clickable link?
I copy the URL from Chrome, and right-click and paste it into the Scrivener window
Are you using
Edit ▸ New Link... with no text in the editor (and thus generating a link with the URL as visible text)?
See above for the exact method I use
Is the document completely empty when doing this, or are you going back and adding a link at the top later? That could include typing in a bit of text and then only selecting the first part of the line and adding a link to it. There are other methods as well that could match that description.*
I first create a title for the document - in Scrivener. I bold, and capitalize the title.
Most often, I select and copy the title of the document from existing text - a lot of the time, that title is from Reddit posts - but not all the time.
Sometimes, I create a title myself, by typing in Scrivener.
I then, typically, copy body text from reddit messages, or from elsewhere (e.g., other documents I might have created, in Word or Scrivener).
Next, I paste that copied body text into Scrivener.
Finally, in the case of taking the title and/or text from a reddit post, I go back to my browser, and copy and paste the URL in to the Scrivener document.
So, you could say that there are quite a few variables at play, but I am quite methodical about how I go about this now.
I am also surprised that this issue seems to only happen a fraction of the time that I use the same methodology.