Same thing happened to me. I ended up finding my files by selecting the Trimble Connect tab (on the left) and then selecting my SketchUp folder. Inside of that is where your files should be. At least that’s where mine where. I think with the new release all of our recent files got cleared out, so our home screen appears blank.
It’s a little funny, but I’m a product designer who is working on a project to onboard people to a new user interface. The designers for SketchUp probably thought long and hard about this, but sometimes even our best efforts as designers have some small hiccups. I know I do. I’d love to see a more onboarding/tours/guides for users for all types of products, but this is a free product, so I can’t complain too much. Keep making awesome products SketchUp team!