I've had issues with two different thunderbolt 3 docks connecting to a 27" Dell 4k monitor using a DisplayPort cable. The laptop recognizes it's hooked up to the monitor and displays it correctly at 60 hz in system report, but the monitor continuously flickers (portions of the screen quickly shift) and turns on and off (every few seconds at best, sometimes several times per second). 2017 MacBook Pro 15" Belkin Thunderbolt 3 Dock Kensington Thunderbolt 3 Dock (bought it when I thought maybe the Belkin was at fault). Dell 2715Q 27" 4K Monitor I've tried with three different display port to display port cables. The third one, I ordered specifically to make sure it was VESA certified 1.2. There is no problem using any of the DisplayPort cables from my PC or a Mini DisplayPort to display port cable with my earlier MacBook Pro. I can also use a USB-C to DisplayPort cable with no problem, both directly from the 2017 MacBook Pro or through either of the Thunderbolt 3 docks. I've also tried swapping around the Belkin and Kensington supplied Thunderbolt 3 cables. Everything else with the docks works. Unfortunately, I'm out of different cables/adaptors, and certainly no more 4k monitors to try out. Although it works, I don't want to tie up one of the dock's limited Thunderbolt 3 ports to go the USB-C to DisplayPort route. Has any one had any similar issues? Appreciate any help.