There is an issue related to the undo implementation of the Polyline tool.
To reproduce this bug follow these steps:
Pick the Polyline tool to add a new element using at least three points
Press the command Ctrl+Z
Try to create a new element. You will notice how the discarded element reappear on the canvas, becoming part of the new element. Once you select a new frame, the Polyline object will disappear.
There is an issue related to the undo implementation of the Polyline tool.
To reproduce this bug follow these steps: