You use "RewriteEngine on" twice (once at the top with the blacklist, and once in the IfModule section).
I'm not a pro with .htaccess so I'm not sure if that's problematic, but it is at least redundant.
I would either move the whole blacklist section inside the IfModule section (removing the duplicate "RewriteEngine on") or else remove the IfModule open/close brackets and remove that second "RewriteEngine on" from there.
If that doesn't sort it out (and it might not, like I said I'm not sure if this is a problem at all) then let us know what happens when you do attempt to visit rewritten urls. Do you get a 500 error? Do you get redirected to the wrong place? Do you get 403 forbidden response pages/codes?