A false positive isn’t really false on an interlock. It’s designed to detect alcohol, and that’s what it’s doing. The alcohol might be from a glass of vodka, or from a Nyquil or some fermented pizza dough. The interlock doesn’t know where it comes from.
States have different reporting requirements. If the interlock detects alcohol and the vehicle doesn’t start, that’s a fail.That’s why they advise you to wash your mouth out after eating if you’re using the interlock.
Any fail will register on your log. I think only NY has real-time reporting. Most states have the interlock shop download the log and send it to whoever looks at it.
If it is a false positive – fruit juice fermentation or whatever – you usually get another chance in 5 minutes or so. If you blow ok the second time, the authorities will figure it’s a mistake and won’t pay attention, presumably. If you blow 3 fails and are locked out for a long time, that’s trouble.