Technical Support wrote:
It is quite possible the grounding in the building (or lack there of) is to blame for the intermittent triggering. It could also be a grounding issue in the extension cord.
Thanks for the response.
After further testing, I now realize that it's the CyberSync Trigger Transmitter that's the problem. The flash will always fire when I press the test button on the AB800 and on the CyberSync Receiver CSR. However, the flash won't always fire when I press the test button on the transmitter.
I ended up completely removing the battery from the transmitter's battery holder and then reinstalled the battery into the transmitter. After that, my AB800 fired everytime. Although my transmitter appears to be working now, I'm concerned that it might crap out on me again in a future shoot. Is this problem with my transmitter a sign that it's on it's last leg or was it just that the battery wasn't installed properly?
In case you're wondering, the battery in my transmitter is (or at least should be) still good as I haven't had the transmitter for more than a year and the red light in the bottom corner isn't blinking.