"Hey Grok" wake word doesn't trigger
Symptom: Nothing happens when you say Hey Grok.
Fix: Turn on voice activation in Controls > Audio > Grok Settings (Tesla's support page; the same settings are also under Grok > Settings). Confirm Premium Connectivity or Wi-Fi, and say it with an American English pronunciation, since the wake word is trained on American English. Press and hold the steering wheel mic button as a fallback.
Sources: [1] [2] [3] [4] [5] [6]
Related: Why isn't "Hey Grok" working in my Tesla? · Grok Activation & session commands