I managed to make it work here:
Follow the steps here (https://collectd.org/wiki/index.php/First_steps) to compile a newer version of collectd, but compile in /root/tmp so it wont get erased. I used the collectd-5.8.1.tar.bz2 package here.
Then rename your current and defective disk.so plugin: mv /usr/lib/collectd/disk.so /usr/lib/collectd/disk.so.old.
At last copy the new compiled version of the plugin: cp /root/tmp/collectd-5.8.1/.libs/disk.so /usr/lib/collectd/
Restart the collectd service: systemctl restart collectd.
Hope it helps.