Microsoft have released an updated build of Windows 10 19H1 to Windows Insiders on the slow ring. Build 18356.16 is a cumulative update to last week’s slow ring build that is designed to test Microsoft’s servicing pipeline.
UPDATE 3/19: Hello Windows Insiders, we have released Windows 10 Insider Preview Build 18356.16 (KB4494123) to Windows Insiders in the Slow ring. This Cumulative Update is a little bit bigger as it is designed to help us test our servicing pipeline with larger updates. This update contains nothing new. We simply updated the version numbers of several components in the OS.
The build was released last week and included the Your Phone mirroring feature.