I have to switch to an HDMI cable to log in, then if I switch back to using the DisplayPort cable it works fine. Other times switching to HDMI cable to log in doesn't work, and I have to force turn off the machine at the back. Then.... 50% of the time it loads up in recovery mode at the reset password screen. Any ideas? I have tried many USB-C to DP cables and the DisplayPort works fine on the monitor as my 2014 MBP works sweet as a nut on it.