I would run the Kodi desktop/GUI at 1080@60 not 4K@30. Use the mode whitelist to permit switching to 4K for media playback when needed but otherwise allow the TV to scale the 1080p skin and 1080p GUI to the panel 4K native resolution using it's native scaling capabilities that do a better job than Kodi and have no load impact on the HTPC device.
NB: The only hardware that doesn't struggle with 4K desktop output is high(er) end Intel CPUs. All ARM boards run the GUI best at 1080p.
Agree thats why we need this fixed so that we dont need to keep UI in 4k 30 just to avoid bug