If you've got games on your PC that use anti-cheat software, such as Fortnite, you haven't been able to install Windows 10 Insider Preview builds from the 19H1 branch, due to a bug that causes a GSOD. Microsoft was waiting on a third-party fix, and the company has updated its blog post for build 18362 to say that "many" games have released those fixes.
The blog post also now says that the block put in place to keep Insiders using the software from upgrading will be removed soon. If you're on the Fast or the Slow ring and you've been blocked from installing the latest build, it should show up in Windows Update shortly.
Windows 10 build 18362 is likely the RTM build for Windows 10 version 1903, meaning that it's the build that non-Insiders will get when it's generally available next month. The fix for this known issue is the removal of a major roadblock for a public release.
There are just two known issues left on the list, one for Creative X-Fi sound cards and one for Realtek SD card readers. Some have reported that the Creative X-Fi issue has been fixed via a driver update, although it hasn't been reflected in the blog post. As for Realtek SD card readers, Microsoft says that it's investigating the issue.