How to get an LG Ultra HD (27UD88) and Macbook Pro 13" 2017 running at 60hz? I recently bought a MacBook Pro 13-inch 2017 and an LG Ultra HD (27UD88) 27" display.
Before buying the display I researched a bit and found no issues in relation to the MacBook Pro.

However, after attaching the screen via the USB-C cable that came along with the display, I only have the option of a 30hz refresh rate.

I've Googled this without finding much - it seems like no one else is having this problem. From a result, I've also learned that my "Display" page in "System Preferences" looks slightly different than a screenshot from an article.


http://www.lg.com/us/monitors/lg-27UD88-W-4k-uhd-led-monitor (LG official page, shows 60hz)
https://9to5mac.com/2016/06/04/how-to-enable-4k-60hz-resolution-2016-macbook/ (speaks of a patch needed for MacBook 2016)
https://www.reddit.com/r/apple/comments/5azoij/2016_macbook_pros_and_lg_27ud88/ (at least one use confirms 60hz with MacBook Pro)
I got it working. I'm not sure exactly how, but here's what I tried, in the order of what I believe fixed it:


Enable DisplayPort 1.2 in screen configuration
Reverse the USB-C cable
Set "Ratio" to "1:1" in screen configuration (I've since tested this and switching it back had no negative effect)


(3) was recommended by a user in a forum thread.

Update 2018-01-29

I've since experienced the problem once more, without changing any settings. Attaching/detaching the cable fixed it.

Update 2018-05-06

After the most recent MacOS update (10.13.4) it no longer downgrades to 30hz, instead, it never comes on. If the cable is dettached, the computer crashes and has to be booted. So far, the only solution I know of is restarting the computer, which works 50 % of the time, and if not, reattach the cable (it usually won't crash after a restart).

This happens after screen sleep and detaching/attaching.

Update 2018-12-13

In this third evolution of the problem (MacOS 10.14.1) the computer no longer crashes. Roughly 9/10 times it will display in 30hz/horrible resolution and all I have to do (sigh) is detach/attach the cable until I hit that 1/10 where it works. It's a daily 5 minutes routine for me.

This setup (MacBook Pro 13" 2017 w/o touch + 27UD88-W) is not recommendable to anyone.