Apple has issued a sub-point release for iOS 12.0.1, knocking out a few bugs involving charging, Wi-Fi connectivity, and sporadic Bluetooth connections.
The update fixes a pair of relatively high-profile issues that were introduced in iOS 12.
The first fix is to charging behavior. In rare occasions, an iPhone or iPad upgraded to iOS 12 didn't start charging when connected to a Lightning cable. The update also fixes a Wi-Fi connection issue, where the iPhone XS family of devices would re-connect to a mixed network on the slower 2.4 GHz band, even if a faster 5 GHz connection was available.
Other fixes include subtitling on video appearing properly, the restoration of the original ".?123" key on the iPad keyboard, and a Bluetooth availability issue.
Both the Wi-Fi and charging issue fixes are included in the iOS 12.1 beta.