I just got an Asus PB287 4K display. I was hoping to use it with the Belkin Thunderbolt Express Dock.
The display works fine when connected directly to my 2014 rMBP, but with the dock it only gives a 30Hz refresh rate.
I spoke to Belkin and they said this was a known issue and would not work the the newer Thunderbolt 2 Express dock, either.
Is there any Thunderbolt dock that will work with 60Hz refresh and a 4K monitor?