Microsoft has been blocking Surface Book 2 users from not updating to the May 2019 Update (1903), due to a problem that caused the dedicated GPU driver for the device to be removed from Device Manager . The problem left SB2 users having to use only the Intel integrated graphics of the laptop.
Now, however, after months and months of waiting, there is finally a solution available, according to Neowin.net. Microsoft has released a set of firmware updates, which not only solve the problem of the display adapter, but improve the "stability" of the battery and solve another problem that involves an unwanted CPU throttling.
Neowin reports that applying firmware updates * should * allow users to update to the May 2019 update (or presumably even the last final update of November 2019), although it may take a bit to remove the lock, since That still appears as a known issue.
If you are a proprietary Surface Book 2, you should check the Windows update for the new firmware versions, or you can manually download the drivers and firmware packages for the innovative Surface device.
Additional readings: firmware updates, Surface Book 2, Windows 10, Windows 10, May 2019 update