SketchUp Viewer not opening

I have loaded the latest SketchUp Viewer on my MacBook Pro (OS 10.14.6) and an iMac (OS 10.13.6) but the Viewer seems to be ‘hanging’. It is not opening, but the indicator dot below the app icon says it is loaded. As far as I know both machines are up to date with software and respective OS…

There appears to be a lack of experience with the SU viewer around here. (Understandable as it is quite new.) I also have posted a similar question on the forum as well as with support - coming to a dead end not able to to open the local folder in VR - but with no responses. Anyone?

@JensCapeTown Is this the mobile viewer or the desktop viewer ?

On a MacBook Pro and an iMac