Hi @k_b
Thank you for your interest in Jetpack Boost and sorry to hear that you are having some trouble with it.
Would you please let us know a little bit more about your current setup such as which theme you are using as well as which plugins do you have activated on your site? Please could you also let us know if you are using external services for improving the performance of your site such as Cloudflare as these types of services can interfere with the creation of the Critical CSS from Jetpack Boost?
If you want to go ahead with the troubleshooting meanwhile, you could try purging any caches that you might have (WordPress cache, Cloudflare cache, etc) and trying to log into your site in an incognito window (to prevent browser cache from interfering) and try it out. Also if you have other Optimization plugins (such as WP Super Cache, W3 Total Cache, WP-Optimize), they can also conflict, so try disabling any you have running to see if that allows you to generate Jetpack Boost’s Critical CSS.
If the above steps don’t change anything, can you take a screenshot of the DevTools Network tab and the Browser Console? Please make sure also to take a screenshot when you’re on the Jetpack Boost dashboard.
You can create and share screenshots using something like Snipboard or Imgur and post the link here.`
I am looking forward to your reply!
Best
— David
Jetpack Boost Developer
