Stunner - Wrong initial Milestone resizing in Case Definition

After new Case Definition (not legacy one) is created and opened, there is initial Milestone on the canvas.

Its resize button is placed on the left upper corner, but it should be placed on the right bottom corner of Milestone.

If try resize it, it is being resized, but the resize button is being moved as well.
In some cases the name and the toolbox of Milestone is being moved too.
In some cases it is also possible to resize it in a way, that the resize button disappear at all.