[numpad0]

As an occasional launch livestream watcher since F9 still had rectangular engine mount, I'd say the real probability of a launch is about 25% for ANY vehicle except for Soyuz from Baikonur and Falcon 9. Everything else could scrub with 24h+ delays at easily 75% chance.

Could be wayward boats and planes, Hydrogen leaks, onboard self diagnostic failure, false hydrogen leak alarms, unstable wireless telemetry connection, upper atmospheric winds and all kinds of weather, frozen plumbings, computers passing out, automatic cutoff due to anomalous vibration at T-1s, anything.

With Soyuz scrubs and failure probabilities finally creeping up, the only vehicle in the world that likely lift off on first try is Falcon 9. Anything else could pause at T-45s and recycle from T-2 hours for couple times, then go all the way to T-0s, and then delay by a week. That's just how most of these things work.