Ui scale has been changed

Hi, I’m using a imac pro base model (Xeon, 32GB ram, Radeon pro vega 56 8GB) with Mojave OS. Whenever I play WoW, this error pops up VERY often:
“The Ui scale has been changed, if you would like to preview the change press the preview button. It is recommended that you reload your User Interface for the best appearance”

I’ve tried all the buttons - “Accept”, “Cancel”, “Preview change”. Nothing seems to solve this for good. Accept or Preview Change will just do a reload ui, and then after a while the same error message pops up again. So I’ve given up and mostly clicked on “Cancel” for the least disruption. However, I hope someone can advise me how to completely stop this message from popping up again as it is incredibly annoying.

My settings:
Display - Fullscreen (Windowed)
Window size - 5120x2880
Resolution scale 100%
Monitor - imac, Anti-aliasing - NONE, Verical sync - Enabled
Graphics quality - 5

Thank you!!

Which add-ons are you using?

I’m using these:
Elvui
Kaliel’s Tracker
Adi Bags
Altoholic
Bonus roll preview
Decursive
EasyScrap
Healbot
Master Plan
Mikscrollingbattletext
Movable Frames
Narcissus
Postal
Scrap Master
Skada
TomTom
Weakauras
WorldquestParty and Worldquesttracker

My guess is the message is coming from Elvui. If you disable it, do you get the same message?