That problem with Blocs refusing the preview after adding fonts is still there. I had an issue where Bodoni was not showing up online when viewed on mobile, despite being visible in preview and they do seem to have been exported.
I decided to delete them all and add them again, but afterwards the page won’t preview. Once again I have Blocs Web Content using 100% of CPU in the activity monitor as well. This seems to happen regularly after adding a number of fonts and requires a restart of Blocs to resolve.
Now trying to save and quit I’ve had this for a few minutes:
I’ve long had issues with Blocs not Previewing at random times, which in my case has nothing to do with fonts. The workaround I found is to click the triangle button (Preview), then quickly click the square “stop?” button, then quickly click the triangle button again. Doing that usually forces Blocs to Preview. Not sure what the root problem of that is, but thankfully I’ve not seen Preview issues in my testing of the latest build.