Hello GoldNick,
I noticed that you have commented and left a link to this thread on the thread with the known issue UE-4659. The issue that you are experiencing is indeed the same issue on that page (I have provided a link below). Thank you for the additional information. This information has already been add to the report (UE-4659). Please feel free to follow the thread linked below for future updates on this issue.
Link: 4.5 UMG Widget Scale not working correctly! - UI - Epic Developer Community Forums
Make it a great day