Weird UMG Bug [4.5]

Hi, I guess I have a bug with UMG:
I created a button and placed it. Now when I set an image in the style tab (any state normal/hovered/etc.), the thumbnail only gets the background color of the image and on the hud, it is broken (weird deformation).

All other buttons (added before 4.5) work properly. It is the Button itself, because every texture gets broken on it, and all textures work on the other buttons.

I made 2 pictures of 1 working and 1 broken button:

I think I have the reason:
When I scale the button down to 6464, I see nothing
When I scale it up to 128
128 like the image, I see the correct image.

This is definitely a bug, because when I copy a “working” button, and paste it in my widget blueprint, then it works. Only creating new ones makes them broken.

Can some developer tell me if this is a known bug?

I have the solution:

I compared the two Strings in my Clipboard and found that there is something missing:

Margin=(Left=0.000000,Top=0.000000,Right=0.000000,Bottom=0.000000)

is missing in the WidgetStyle section. Adding this works.
Can it be fixed?