I've confirmed that this bug is also triggered by using the Rotate function in the Transform dialog.
(Not coincidentally: I use the Transform dialog so I can use a specific degree rotation. That way I can "undo" the rotation by rotating it back for further edits to the group before re-rotating it. A "remove all transforms" function would alleviate the need to do it this way.)
I've confirmed that this bug is also triggered by using the Rotate function in the Transform dialog.
(Not coincidentally: I use the Transform dialog so I can use a specific degree rotation. That way I can "undo" the rotation by rotating it back for further edits to the group before re-rotating it. A "remove all transforms" function would alleviate the need to do it this way.)