(Probably a duplicate, but I can't find it.) The initial report of that bug is on that conversation.
If you share a link that has highlights, highlights are not visible (video)
The user who experiences it has tried it using
- Firefox Developer Edition: 57.0b6
- Safari 11.0 (12604.1.38.1.7)
- Chrome 61.0.3163.100
I don't manage to reproduce that bug using
- Firefox 56
- Chrome 61.0.3163.100