Video: https://youtu.be/5-oZMxIOcVg
Instructions from Video:
When you add in windows into Envisioneer the framing around that window is also added in based on the Framing Options you have set up for that location. In some designs you may have multiple windows lined up in a row and your first thought is to add in each of those windows individually. This will create small sections of wall in between each window and Trim that may overlap depending on the size selected. The better option is to add in one mulled window unit.
Select Insert>Windows>Window.
In the catalog panel to the right, select a window and then left-click to insert it into your model.
Right-click and select Finish.
Left-click to select the inserted window and then right-click to select Properties.
In the Windows dialog box, under the Basic tab set the a-Window Width to the overall width of the entire window. Change the # of Horizontal Panels to be the number of mulled windows that comprise this entire window. Change the name of the Window to reflect the new mulled unit. Select the Quantity tab.
Select the Mark option and type in a new mark that describes the entire mulled window unit. Click OK.
This will give you one cased opening that is displaying correctly in both 2D and 3D.