I upgraded my development site for a Joomla 4 installation, to the latest T4 plugin. And now there is no preview in the site template styles screen. If I go to the Layout Settings and turn on the Layout Position Preview button, it resets the page and I can continue working, but it must be done every single time I go into the template styles. This is most annoying. I've checked it on several Joomlart Joomla 4.x sites, and they are all doing the same thing after updating to the latest T4 plugin.
Here are several screenshots. The first is what I see when I open the template style for the homepage:
And this one is after turning on the preview module positions button: