Windows 10 1709 update removed my 3 monitor setup

[wavemaster]

My set up is a Dell Precision mobile workstation in a dock, and two monitors attached. Effectively I have 3 screens. Visual Studio on one, SQL Server Management Studio on one, and the browser on the third.

Perfect arrangement for a web developer.

After the 1709 update Windows 10 no longer allows 3 monitors, only two.

This is a major disruption of my workflow.

[#2]

Its possible you just need a driver update. I would check for new drivers on Dells website. You could also remove your current drivers, restart and then update them in device manager. 

[#3]

No new drivers available.

[#4]

Please try  "Project" --> "Duplicate" and after screen-duplication  immediately press "Extend".

Maybe this might help