Preview mode is not showing site that uses Volt CMS.
Preview mode does show non-Volt CMS sites.
When I go to preview mode in site using Volt CMS site after opening preview of non-Volt site the preview window shows the recently opened non-Volt site.
I don’t know what bits are Volt, but I’m seeing this on the Chanting Tips page, which I guessed was a Volt-populated page.
If you still have problems, I’d export the whole site again to a clean folder (ie: not overwriting your previous export) and upload again and go from there.
I had a problem with Blocs exporting a site that looked like I was logged into Volt online (showing the pale green boxes ready for editing) the other day, but a clean re-export solved that problem.
Many thanks Jannis - problem resolved following a re-install of Blocs - just one of this things I guess - all the squiggles around the Chanting Tips page are accurately reproduced diacritics.