The release health dashboard page has been updated to point to Version 1909:
And we have a compatibility hold for people using Realtek Bluetooth adapters:
Issue: Unable to discover or connect to Bluetooth devices using some Realtek adapters
Details: Microsoft has identified compatibility issues with some driver versions for Bluetooth radios made by Realtek. To safeguard your update experience, we have applied a compatibility hold on devices with affected driver versions for Realtek Bluetooth radios from being offered Windows 10, version 1903 or Windows Server, version 1903 until the driver has been updated.
Resolution: install driver version 1.5.1012 or later to upgrade to 1903 or 1909.