In a normal detail panel, each element has its own SDetailSingleItemRow and are mostly uniformly sized with some exceptions of having a few bigger rows (i.e. asset pickers). However, these layers are all shoved into a single row which can become huge and problematic for scrolling. It seems like a lot of custom work was done here and a fix may require a total rework.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-100371 in the post.