Could be that although you have 755/777 permissions, SELinux is blocking httpd from writing/creating dirs.:
chcon -R -t httpd_sys_content_t /var/www/html
sudo chcon -R -t httpd_sys_rw_content_t /var/www/mrr/public/textpipe
  
sudo chgrp apache -R /var/www/html/files
chmod g+s .