@TheAsocial @CaseySJ Thank you very much guys for letting me know. I'm very interested in knowing this and honestly a bit surprised to see this LG display working just OOB, without any issues. That's great achievement! Well, I think it's time for me to consider switching to some new displays this year, I suppose.
For now, I'm with my new Dell U2719D, but will be definitely adding something 5k/Retina, glossy, IPS as a main display later this year.
Btw, guys. My drama continues. Just got another response from Gigabyte support team in terms of Titan Ridge and Apple Thunderbolt Display issue. Their engineering/validation team confirmed to me that Titan Ridge in Z390 Designare, due to its limitations doesn't support any Thunderbolt 2 devices through adapters, at all. I was like, seriously? You guys should be joking, right, because so many people I know running various TB2 devices through adapters with no problems. So they basically saying, that Titan Ridge only supports TB3 devices. They definitely doesn't know what they're doing. I have no power to continue the conversation with them. It's like talking to the walls.