Microsoft recently released new firmware for the Surface Book 2 to enhance support for the Windows 10 April 2018 Update. The firmware improves hibernation and should be rolling out now on Windows Update to devices across the world (via Thurrott.com)
As usual, Microsoft has not yet listed the firmware update in the Surface Book 2 Update History page, but the word on the update was spread on the TechNet blog. According to Microsoft's Brandon Records, this update bumps up Surface Integration to version 4.7.1360.
If the update is not showing up in Windows Update, you can manually download it in MSI format by checking here. The Surface Book 2 last got updates in January, then to address the Meltdown and Spectre security flaws. There was also a set of updates that rolled out to Windows Insiders, though it was not clear what is new.