Walk/ Fly mode greyed out _not working

Does anyone know why this is greyed out? space bar doesn’t do anything. this is on windows system. this also happens on my MAC

also- when I turn off “synchronize views” my enscape window view flies to the exterior of the building. What is happening?

Make sure in SketchUp you have your views in perspective. Sometimes I forget to reset it back from parallel projection, that’s when the issue you mentioned occurs.