Apple has just released iOS 12 Beta 4 to developers.
In the newest developer beta, Apple has addressed some issues and fixed some bugs that were present in the third beta.
According to Apple's release notes for the fourth beta, there are several issues with Screen Time, the App Store, and Siri Shortcuts.
Screen Time: the data may not be synced between devices. Apple recommends restarting the device to fix this issue.
App Store: apps might fail to download the first time.
Siri Shortcuts: it may not work while using CarPlay and HomePod. Also, it may not be restored from an iCloud backup, it may not work when the device is locked, and SiriKit queries could be delayed or might not even work.