I've noticed lately when I post a hyperlink into some highlighted text the link will appear elsewhere in the post.
I'll try and repro this now
Example: McAfee Customer Service
OK that seemed to work OK but often the URL will appear spelled out in full, right after the applicable text.
This was the post which I had to subsequently edit to sort the problem out (about the 5th such instance in the last few days):
Perhaps it's my browser? Although I doubt it.
Mozilla Firefox 54 (64-bit)