Drag & Drop of course elements in courseeditor

When sorting elements in the course editor sometime the behaviour is other than expected.

Elements:

A | B | C if i want to change to B | A | C  i would drag & drop A in between B and C but then I get  B | C | A   (see what_I_want.png and what_I_get.png)

Somehow this occours only if I drag an item downwards..

If I rearrange the elements upwards everything works as intended...