I noticed this after updating an existing site to 6.3 RC1 – but even after downgrading that site, it appears as if this issue might have been present in the prior Pro version too. So not entirely sure if it’s a beta issue (or I somehow broke this site myself ).
I’m also unable to repro on a different test site.
In any event, in the site I had built ~2 years ago, I had a variety of custom CSS that was entered into the Header/Page/Layout CSS editors (not the Global CSS). And while that CSS is still previewing correctly within the Pro builder, the CSS is not making its way to the published site for some reason.
For example, I have a custom background color targeting the body of certain post types. Looks fine in the preview, but uses the Theme Options background color on the published posts (and I can’t find the CSS in the output when inspecting).
I completely disabled all plugins in a staging environment to ensure there wasn’t a conflict there, but no dice. Still a problem.
Not sure if anybody else has seen this on upgrade. I’ll get you login credentials if you want to poke around @Charlie. Thanks!