After updating to 10.13.4 developer beta 1, DisplayPort on my Thunderbolt 3 Toshiba dock stopped working.
When attaching a display, the screen blinks, like it briefly detects, but doesn't appear in MacOS. It does mess up wallpapers on my desktops when connected, though (some of them start showing clear blue background, Win95-style! 🙂).
Also, HDMI sound output seems to work and shows the display, it's just the graphics that doesn't work.
I'll try attaching it directly to my Macbook if I find the right cable somewhere.
Anyone else?