I have had no problem getting rpi to work on my Nano PI Neo via a GPIO. I selected GPIO 2, which is available. Is 92 available? Also, with RPI, you don't need to "export" the GPIO, just tell rpi which GPIO to use and it does the work for you:
From my /etc/rc.local:
/usr/local/bin/rpi_gpio_ntp -N 1 -g 2
Here I am specifying GPIO 2.
You can also test by doing the following:
root@Wilcutt:~# rpi_gpio_ntp -N 1 -g 2 -d
rpi_gpio_ntp v1.5, (C) 2013-2015 by
folkert@vanheusden.comNTP unit : 1
GPIO pin : 2
GPIO pout: -1
Fudge : 0.000000000
"Fork into the background" disabled because of debug mode.
1528637369.482893215] interrupt #1, 0 wraps, offset 0.482893s nan/0.482893/nan
1528637370.482790391] interrupt #2, 0 wraps, offset 0.482790s 0.482790/0.482842/nan
1528637371.482779647] interrupt #3, 0 wraps, offset 0.482780s 0.482785/0.482821/nan
(etc)
Again, my GPIO is #2.
I'm going to guess your GPIO pin is not a good one to choose.
Bryan