I use the same gpio library and all pins are working on my OPi Zero.
It may be worth re-soldering pin 9 on the IDC header and see if the soldered
connection is at fault.
Below is a very quick bash script to set all pins as outputs, activate them,
then turn off all pins you can use as a check.
There's probably more efficient ways of doing the same thing
#!/bin/bash
gpio reset;
sleep 1;
for n in {0..30};
do
gpio mode $n out;
gpio write $n on;
done
gpio readall
sleep 3
for n in {0..30};
do
gpio write $n off;
done
gpio readall;
sleep 3;
gpio reset
hal8k got a reaction from Dino in Orange PI Zero - GPIO does not work?