This problem continues to resurface over and over.
IMPORTANT! Ongoing problem since 2008
Problem: If you are unable to create .htaccess files with AutoMagic or edit .htaccess files with the built-in editor or you are seeing 404 errors when trying to edit .htaccess files or use AutoMagic and Quarantine does not work period then your site is using the broken cPanel HotLink Protection Tool. It has been broken since 2008 and it also breaks many other WordPress features such as the Plugin Editor and too many other things in WordPress to list here.
Solution: There is only one way to block the broken cPanel HotLink Protection tool, since enabling and disabling it is also broken - you cannot turn it off. You need to lock your Root .htaccess file with F-Lock and log into cPanel and delete all code that you see in the HotLink Protection tool window. If you unlock your Root .htaccess file at a later time and WordPress and BPS and ARQ are not working correctly again then you will need to repeat these steps to fix the problem again as this broken tool will probably do the same thing again as soon as your Root .htaccess file is unlocked.
There is example HotLink Protection .htaccess coding included in the BPS Root .htaccess file. It is commented out so if you would like to still have HotLink Protection for your website then uncomment that example .htaccess code and add your actual domain name to the example HotLink Protection .htaccess code.