-Two different pages (from self-made script template) open in split-screen mode.
-Attempted to change an element in the bottom screen with a keyboard shortcut. Instead, Scrivener changed the same element in the top screen.
-The bug only seems to occur when trying to change the bottom screen element, the top works fine.
What keyboard shortcut did you use? If you used the Function key with the letter assigned to the item in the menu, then there’s no guarantee that will work as that is an OS X feature, not a Scrivener one. In Scrivener, the idea is that you hit shift-cmd-Y to open the elements menu and then type the letter associated with the item in the menu - or, even faster, you can just use the opt-cmd-1 - 9 keys without needing to bring the menu up at all. However, OS X has something built into it whereby if hit Function + a letter in a pop-up menu, it will perform the command associated with the menu item. But in this case, OS X just looks for the first pop-up button it can find with that letter associated with it, and Scrivener has no say over which item OS X chooses. And OS X has no idea about what is focussed or which one should be used, so it may make the wrong decision.
All the best,
Keith