When following step 3
on those instructions, did you also read and follow this part?
Note that when we use >> this is going to append the rule to our ModSecurity configuration file, so we don't overwrite any previous rules we've allowed as well. If you don't already have your ModSecurity configuration file included in your Apache configuration, be sure to follow my guide on how to enable ModSecurity include and create a configuration file which covers this.
It's also important to remember you can't have the SecRuleEngine Off rule still in your ModSecurity configuration file if you're just disabling specific rules, as it will completely turn off ModSecurity.
What's the domain name you're having these issues with?