I happen to have 2 4K monitors and a Fury as well actually.

I actually couldn't run Wayland at all for some time, perhaps it was fixed by:
mutter (3.22.2-3) unstable; urgency=medium

  [ Jeremy Bicha ]
  * Add git_flush_all_swap_notifies_on_idle.patch:
    - Add patch from 3.22 branch that fixes freezes with multiple monitors
      on Wayland
landing in my Ubuntu repos.

Anyway, today I can run gnome shell in Wayland and I don't have any flickering.

Do you have the very latest firmware from
http://git.kernel.org/cgit/linux/kernel/git/firmware/linux-firmware.git ?

Guess the devs always like dmesg and xorg... wait nevermind that last part. :-)
Maybe journalctl /usr/bin/gnome-shell  ?