IE: Column in doublecolumn widget disappears after drag & drop

[Tade0]

Steps to reproduce

1. Open ​http://tests.ckeditor.dev:1030/tests/plugins/manual/widget/block
2. Create a code snippet widget and a doublecolumn widget after it.
3. Cut & paste the code snippet widget to the upper field of the doublecolumn widget.
4. Drag & drop the code snippet widget to the lower field of the doublecolumn widget.

Expected result

The code snippet widget is dropped to the lower field and nothing else happens.

Actual result

The code snippet widget is dropped to the lower field and the upper field disappears.

Other details (browser, OS, CKEditor version, installed plugins)

IE11