Drag and Drop on Fields with preview-field attribute doesn´t work

Hi, i made two fields with previewfield attribute- one for a sprite and one for a prefab. On both i can´t drag and drop things. On Sprite field - Drag and Drop a sprite Image - nothing happens - Drag and Drop a png - Unity crashes On GameObject(Prefab) field unity crashes when putting a prefab on it.

With select function from the preview window it works to select things but thats of cause a horrible workflow.

I´m on OSX, Unity 2017.3f