I am not support but I think the query string (?ver=) is preventing it. What you can try doing is copy paste the entire url with ?=ver= instead of automatic inline and see if it gets inlined. If it doesnt, remove the query strings. There are plugins that do it, maybe also WP fastest cache has that option. I hope it will work for you.
@garyfo if you indeed enabled the option just like in the following print screen: https://i.ibb.co/zfJ3NXs/wpacu-enable-inline-css.jpg – then it should have worked. Perhaps something is interfering with it. If you’re comfortable sharing your website URL, please do so, otherwise, you can privately write to me via https://www.gabelivan.com/contact/.
@dan14 /?ver= should not have anything to do with this as that’s the default WordPress query string added to enqueued CSS/JS files. Also, removing query strings is not the best idea because if the information from the CSS file changes, “ver” will have a new value, and the browser needs to download the new content, not use the old one from its cache. In fact. This is really not such a thing anymore (it used to be part of GTmetrix scoring), removing query strings from static resources. If you check this post – https://docs.wp-rocket.me/article/56-remove-query-string-from-static-resources – and scroll to “Don’t use simplified solutions!” you will understand what I mean.
@garyfo as I replied to you privately, I’ll post an explanation about the problem you were having so other users would be aware of it in case something like this happens.
Some of the CSS files you mentioned they weren’t inlined had over 3 KB in size. When you checked the size in GTmetrix (as that’s what the print screen you provided suggests), you were shown with a smaller size as some of them were gzipped (read more about it here: https://varvy.com/pagespeed/enable-compression.html). You have to use the browser’s console or download the file and determine the actual size. All one has to do in this case is to increase the size from 3 KB (from “Inline Stylesheet (.css) Files Smaller Than” within “Inline CSS Files”) to a higher number such as 10 KB.
