Microsoft has been releasing new Windows 10 Insider Previews pretty frequently lately, with today's build 17738 being the most recent. But today is still Tuesday, and that means a new build of Windows Server 2019 and a new SDK Insider Preview.
Both of the new builds are 17733, and unfortunately, Microsoft hasn't published a blog post about either of them to describe what's new. Sadly, it's pretty common for Microsoft to be unable to publish a changelog at the same time that it actually offers something.
There probably won't be many new features anyway, given that we're in the final stretch of Windows 10 Redstone 5 development. If you're testing Windows Server 2019, Microsoft wants you to report feedback on in-place OS upgrades from Windows Server 2012 R2 or Windows Server 2016, along with application compatibility.
There's also a new Windows Admin Center preview, which is version 1808, along with a new Server Core App Compatibility FoD Preview. To download either of those, along with Windows Server 2019 build 17733, you can find them here. For Windows 10 SDK Preview build 17733, you can find it here.