Submenu artifacts. Radeon RX 580 + Plasma + amdgpu

Hello all,

I have continuing issues with display artifacts from drop down menus.
Across all applications.

Photo showing behavior:
-> twitching mouse to other drop downs and back generally clears issue
-> happens consistently from boot through many days of work uptime

Quick summary:

Leap 42.3 installed Oct 2017, regular updates via Yast

Workstation: dual E5-2698 v3

Linux linux 4.4.92-31-default #1 SMP Sun Oct 22 06:56:24 UTC 2017
             (1d80e8a) x86_64 x86_64 x86_64 GNU/Linux
plasmashell 5.8.7 

Video: ASUS Radeon RX 580 O4G Dual-fan OC Edition

Display:  ASUS PB287Q Monitor - 28" 4K UHD (running at 3840x2160)

Kernel driver in use: amdgpu

More details (lspci, glxinfo, xrandr):
Listing from /var/log/Xorg.0.log

Observation: no artifacts present when running Kubuntu 17.04 (Live)

Suggestions are most appreciated.

Having used various Linux distributions for 15+ yrs, this setup with OS
42.3 and Plasma is very compatible with my productivity and engineering
software (including VMware WS-Pro). A real pleasure to use.