Content hidden in SPA route

I’m trying my hand at building a SPA and started with this: https://docs.wappler.io/t/creating-single-page-apps-spa/6583

My problem is that when I navigate to a route, the contents of that route do not show on the page. I get a completely blank page. If I open dev tools and inspect the page, everything seems to be all there, but with a html tag at the top with visibility of hidden:

If I uncheck that style, the contents show, but everything is disabled.
Any idea what could be wrong?
Thanks, Dan