When the carousel is open, the next image on the right of the current window prevents you from using the scroll bar. If you tap or click your cursor on the scroll bar, the next image displays and you can't scroll for the comments.
If you put your cursor on the scroll bar in the area of the next picture, and attempt to slide the scroll bar, you pick up the next picture with your cursor and move the next picture usually to a new browser window.
Here's the gallery on my 'test site'.
Thanks for any help,
I found a previous thread for this issue. It's closed & won't resolve my problem.
Jetpack fixed this issue from a support ticket, but my browser issue is with Safari not Firefox.