I have workarounds, but it is a pain in the ass to do every time I leave the mac for 10 minutes and come back to find it in sleep mode and have to go through this. It will work fine with HDMI and the mini, but when the Mac Mini goes to sleep hooked up over Thunderbolt, I can't get it to connect to the monitor without a bunch of tricks (unplugging/plugging back in the cable, turning display off/on, plugging in HDMI to confirm Mac is awake and then switch to T3, changing input off T3 then back to T3. Attempting to use the Thunderbolt 3 with my new Mac Mini is a bit disappointing though. This monitor looks great and works perfect on my desk with my laptop over HDMI. Hopefully LG or Apple comes up with a solution. The pain comes when I start my Mac Mini up in the morning and it takes about 15 minutes turning on the monitor, turning off the Mac Mini multiple times for the OS to be seen on the monitor. Type in the word Mac, then review the comments given. Select it and scroll down until you get to the part to ask a question. Window shop on Amazon for the monitor size you would like. I would recommend doing your homework if you choose not to by the LG monitors that Apple is specifically selling.
