Unfortunately, this still happens to me too. After repeatedly trying different work-arounds I found this to be the easiest way to select my vport: 1] select the Pspace tab you need to be in 2] in 'Properties' palette click on 'Quick Select' at top right then in the 'Object type' drop-down select 'Viewport. "Value' field is ByLayer (see attached 'Quick Select' screen shot for settings). 3] Click OK and you should see the vport highlighted with grips.
