In general I really like the usability and ergonomics of my Canon 6D. The menu system is very easy and intuitive to understand and the camera is a pleasure to hold in the hand with very well thought button placements.
However so far I have experienced two unexpected side effects with settings that took me quite a while to figure out as the relationships between the implication and the actual setting do not sound logical to me at first glance.
Silent Live View vs. Flash Triggering
In case your manual, remote controlled flashes stop working after switching to live view (or remote shooting through the mobile app) make sure that Silent Live View shooting is set to disabled. On the Canon 6D you find this setting on the second live view settings screen on the top. If this is set to either Mode 1 or Mode 2 external manual flashes will not be triggered at all, when shooting in live view. It still does work however using the view finder.
As the default factory setting here is set to Mode 1 this took me quite a while to figure out.
Tethering: USB Port Not Working?
Just recently I wanted to try out tethering using the USB port, as my computer has a corporate firewall installed that prevents wireless tethering, plus it does not support hosted networks. However Lightroom simply did not recognize the camera. Even Windows 10's device manager did not detect it. I already started thinking that my camera's USB port was damaged as another Canon camera (my daughter's EOS 1200D) just worked right away.
The solution? Disable the built-in Wi-Fi.
Once disabled, the USB port was immediately resurrected from the dead and just started working as expected.