Is anyone else having issues with comment box resizing? Specifically when I grab the corner and drag to resize, the mouse cursor moves beyond the expanding comment box. As in the cursor moves well ahead of the grabbed edge while the grabbed edge never makes it out to where the mouse cursor is. This sounds very similar to the following bug report from 2017 Unreal Engine Issues and Bug Tracker (UE-51018).
This certainly wasn’t a thing in EA but I can’t speak for Preview 1. As a test I brought up a project in 4.27.2 and the comment boxes resize as they should by following the mouse cursor precisely.