Hi NenadM,
Interesting, this may have been a recent addition to the editor that I missed. I tested on my end and sure enough you can view variables in scope on break nodes, I will keep this in mind for the future. I did a bit more digging and remembered that there is a bug report, UE-20846, that is specifically for variables appearing not in scope within Custom Functions. Can you try this in a custom event within the main event graph to see if the error is reproducible there?