Hello, I don’t know what causes this but I had the exact same issue in Blender on the exact same left shoulder, right foot and forearm. Inside of Unreal itself you need to set the BONES to use the SKELETON and not the ANIMATION. I guess it offsets some of the positions. I have a tutorial where I do character animation and fix a similar issue. Have a look at the video it should help you solve the problem. https://youtu.be/DKfOaIXCN90?t=641
If you look at my earlier videos you will see that I have a character running around with the same deformations.