Yea, this is Continuum for you. Automatically switches to the correct mode, does it? Well, only when it feels like it. One of my devices is a convertible, and when I swing it round into tent, presentation or tablet positions W10 does indeed change modes appropriately. If I switch off the PC however, and then switch it on again later, it will power up in whatever mode it was in when I last used it and fails to detect the position the device is in. This happens for everyone who uses Continuum, not just me. It makes the concept pretty unusable as you have to manually take control. All this when W8 implicitly switched between modes so that when you used the desktop, you had a desktop style of operation. Swing your device round to a touch position and Metro was already there. Now we get a fiddly mess.
And the reason this happens? MS forgot to add the option to power on in the appropriate mode, as you can see in the Continuum options in the settings app. That's all there is to it. How this was missed in testing totally confounds me, as it was so widely trialled. But can we persuade MS to get off their behinds and enable the option so that Continuum works as designed/advertised? You guess.
Could be improved simply by adding a key press shortcut and a script control to switch between modes (like most other Windows functions allow), then we could write our own routines to make W10 operate correctly and even make swipes or mouse buttons flick this unnecessary Metro mode switch. Unfortunately this was removed during pre-release testing to ensure users are not able to fix things because that would be too easy.
One day, perhaps they will take a look at their flagship feature of Windows 10 and decide to make it work properly. Hopefully before Windows 11 is released.