Noticing that there is no scrollbar for Structures UI. This happens for the Structure and Default Value sections.
When adding a new variable you see scrollbars appears for a second before disappearing.
Regression: Yes this works in 4.13. In 4.13 the two sections are side by side though not sure if that is related.
Result: List expands but no scrollbar appears.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-39059 in the post.