I can’t post a bug report, it does not let me. However, I will post the information through this reply.
You can reproduce it by adding a UICorner to a UI element and then selecting the UI element, and you may see the CornerRadius property of the UICorner object decreasing as you select it. This doesn’t always happen for me, though recently, this has been happening most of the time.
This started happening pretty much after the release of UICorners.