I'm having issues with my GH5 failing to focus using the back button focus when my external monitor (DP4) is connected.   Without the DP4 connected back button focus works as expected. I have it set to lock when pressed.   Connect DP4 backbutton focus no longer works. Pressing the shutter button half way is the only way to auto focus   Setting the focus via back button then turning on the DP4 cancels the focus.     Has anyone had this issue with their external monitor be it a DP4 or som