Disappearing Save As.. dialog in SketchUp 2016 Win Release 1 (16.0.19912) and how to work around it:

Problem: In SketchUp 2016 Windows Release One (16.0.19912), when you choose Save As.. location for the .xcs file, a Save as dialog will open. If you move your mouse cursor anywhere in the SketchUp Window, the dialog will disappear. In reality, the Save as...dialog is "pushed" back behind the SketchUp 2016 Window.

Solution: Minimize the SketchUp 2016 Window and you will see the Save as...dialog on your desktop. Pick the folder location you want to save your .xcs file to. Click OK. Then maximize your SketchUp Window.

Why has this happened in SketchUp 2016 Windows versions? Something changed in SketchUp 2016 Windows where the focus of SketchUp is always in the foreground so that when a 3rd party plug-in panel is displayed, this panel is forced to the background. This is a recognized problem in SketchUp 2016 Windows and will likely be fixed in a later maintenance release. Cadalog, Inc. is also trying to find a work around to this issue.

When you start a new Viso3D session in SketchUp 2016, you are prompted to Save As...the .xcs file you are about to create. If your SketchUp 2016 Window is maximize, it's likely this dialog will seem to disappear when you move your mouse cursor across the SketchUp 2016 Window.

Minimize the SketchUp 2016 Window and you will see the Save as...dialog box in your Windows desktop. Select the folder where you will save the .xcs file. Then select OK and close the Save as...dialog. Finally maximize the SketchUp Window.