Making a wild guess that it was a Circle K-station that you went to? They were quite early to the market with fast chargers, and had a lot of reliability issues with some of the chargers. Like you suggested, it's usually software related, and you can often get them to work by just power-cycling them using the emergency stop button. If you hear the loud click from the metal contacts or the charger latches with the port and it doesn't start charging it's almost always a software glitch that a restart will fix.
For regular AC-charging all the logic is in the car, so the only thing you really need is some safety features on the outside, typically some ground fault protection and so on. But when you use a DC fast charger the charger itself and the cars battery management system has to work together, which I imagine can cause all kinds of edge cases where people have interpreted the standards differently. It didn't help that there were multiple different standards early on.
For regular AC-charging all the logic is in the car, so the only thing you really need is some safety features on the outside, typically some ground fault protection and so on. But when you use a DC fast charger the charger itself and the cars battery management system has to work together, which I imagine can cause all kinds of edge cases where people have interpreted the standards differently. It didn't help that there were multiple different standards early on.