We are currently troubleshooting and fixing a login in problem with SketchUp for Web and other SketchUp products. I’ll post here again as soon as we are up and running.
@Box You’re right that this is a big downside for the web app of SketchUp. We have some plans on how to address this. For the desktop app, one’s login is valid for 28 days; making the app more resilient to login outages.