Box within Group rendering issues

Placing a box within a group produces the following (drag around to see the result):

**Test case:** https://codepen.io/MarioD/pen/vwQErz

Start by reproducing the rendering problem in the linked CodePen test case and drag the box within the group to observe the result. Trace the JavaScript rendering path used by the demo, then verify that a box inside a group renders correctly while dragging and that the reduced test case no longer shows the reported issue.

Written by the indexing model from the issue text.