Ever since Apple first announced iOS 12, macOS Mojave, watchOS 5, and tvOS 12 last month, the company has been releasing new betas every two weeks like clockwork. The last one was on July 3, which means that it's time for a new round.
iOS 12 build 16A5327f once again provides an array of fixes. All known issues with third-party apps have been resolved, so Netflix and Fortnite should both work properly. You might get an error message when installing an app from the App Store though. Also, the cellular status bar on an iPhone X lock screen might be inaccurate, so don't worry too much about that.
For macOS 10.14 Mojave build 18A336e, there are some new known issues with the brand new MacBook Pro models, as brightness settings might not work. Other PCs are affected by different issues, such as the Mac Pro from 2010 and 2012 being unable to sign into FaceTime or iMessage. There's also an issue where if you print out a route from Maps while your PC is in dark mode, it won't show arrows.
watchOS 5 build 16R5322d looks better than it did on the last build, although there are still a bunch of issues. Siri shortcuts might throw an error, and the Watch might crash when pairing with a new iPhone. Haptics settings sync should be working properly now though, as should Run and Walk workout reminders.
Finally, tvOS 12 build 16J5313d is the only one that doesn't list any new issues, so it's all about fixes. As always though, you should check out the release notes on Apple Developer before installing these new builds.
This is a sort of halfway point for development, and these builds should start to get pretty good from here on in. You can expect to see them finalized in mid-September, with the GM seeds published after the iPhone launch, and generally available in late September.