Object import fails from AutoDESK Infraworks

I need to import Infraworks models into SketchUp but even though I save as an .FBX file, it won’t load the model in. If I download a free .FBX file in from the web, works perfectly. I’m using 2018 version of SketchUp because I had problems loading 2019 files into Lumion Pro…

Any advice would be great. I can import from Infraworks as a .DAE file but, of course, it’s three times the size!