To allow the robots to crawl all CSS and JS files we have used the following code:Allow: /*.css$Allow: /*.js$But, some CSS and JS are still being blocked as stated when using the mobile friendly test from Google.Does the location of the line of code in the robots.txt file matter?Are there instances were the line of code will be ignored? 
Wildcard matches in robots.txt that allow crawling of all JS and CSS are not working
robots.txt
Robots.txt uses the longest rule that matches.   So when your rules areDisallow: /directoryAllow: /*.jsThen /directory/file.js would be blocked.   Both rules match, and the longer one (the disallow rule) takes precedence.  See this article which explains it.One work around might be to use lots of stars in your wild card rules to make them longer than your other rules:Allow: /********************.jsHere are some screenshots from Google's robots.txt testing tool showing the technique working: